diff --git a/.circleci/config.yml b/.circleci/config.yml
index 555721e..f61cc95 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -42,11 +42,11 @@ jobs:
       - store_artifacts:
           path: htmlcov
       - store_artifacts:
-          path: debian/little-brother_0.3.10_82.deb
+          path: debian/little-brother_0.3.11_82.deb
       - persist_to_workspace:
           root: debian
           paths:
-            - little-brother_0.3.10_82.deb
+            - little-brother_0.3.11_82.deb
   build_pypi:
     #working_directory: ~
     docker:
@@ -61,11 +61,11 @@ jobs:
 
       - run: PYTHONPATH=contrib/python_base_app python3 ci_toolbox.py --execute-stage BUILD --use-dev-dir=.
       - store_artifacts:
-          path: "dist/little-brother-0.3.10.tar.gz"
+          path: "dist/little-brother-0.3.11.tar.gz"
       - persist_to_workspace:
           root: dist
           paths:
-            - "little-brother-0.3.10.tar.gz"
+            - "little-brother-0.3.11.tar.gz"
   install_pypi:
     #working_directory: ~
     docker:
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b4a45ea..34bafb4 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -62,7 +62,7 @@ build_pypi:
   artifacts:
       when: always
       paths:
-        - dist/little-brother-0.3.10.tar.gz
+        - dist/little-brother-0.3.11.tar.gz
   variables:
     # Suppress automatic checkout for all sub modules
     GIT_SUBMODULE_STRATEGY: recursive
diff --git a/CHANGES.md b/CHANGES.md
index d8c5fb6..a789fd4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,15 @@
 
 This document lists all changes of `LittleBrother` with the most recent changes at the top.
 
+## Version 0.3.11 Revision 82 (February 6th, 2021)
+
+*   Closes #28, see [here](https://github.com/marcus67/little_brother/issues/28)
+*   Closes #113, see [here](https://github.com/marcus67/little_brother/issues/113)
+*   Closes #112, see [here](https://github.com/marcus67/little_brother/issues/112) (presumably)
+*   Closes #58, see [here](https://github.com/marcus67/little_brother/issues/58) (presumably)
+*   Closes #110, see [here](https://github.com/marcus67/little_brother/issues/110)
+*   Closes #86, see [here](https://github.com/marcus67/little_brother/issues/86)
+
 ## Version 0.3.10 Revision 81 (January 17th, 2021)
 
 *   Upgrade to python_base_app 0.2.9
diff --git a/bin/generic-install.sh b/bin/generic-install.sh
index 65cad16..32fa8ad 100755
--- a/bin/generic-install.sh
+++ b/bin/generic-install.sh
@@ -47,20 +47,20 @@ if [ ! "$EUID" == "0" ] ; then
 fi
 
 echo "Checking if all Pip packages have been downloaded to $TMP_DIR..."
-if [ ! -f $TMP_DIR/little-brother-0.3.10.tar.gz ] ; then
-  echo "ERROR: package little-brother-0.3.10.tar.gz not found in $TMP_DIR!"
+if [ ! -f $TMP_DIR/little-brother-0.3.11.tar.gz ] ; then
+  echo "ERROR: package little-brother-0.3.11.tar.gz not found in $TMP_DIR!"
   echo "Download from test.pypi.org and execute again."
   exit 2
 else
-  echo "Package little-brother-0.3.10.tar.gz was found."
+  echo "Package little-brother-0.3.11.tar.gz was found."
 fi
 
-if [ ! -f $TMP_DIR/python-base-app-0.2.9.tar.gz ] ; then
-  echo "ERROR: package python-base-app-0.2.9.tar.gz not found in $TMP_DIR!"
+if [ ! -f $TMP_DIR/python-base-app-0.2.13.tar.gz ] ; then
+  echo "ERROR: package python-base-app-0.2.13.tar.gz not found in $TMP_DIR!"
   echo "Download from test.pypi.org and execute again."
   exit 2
 else
-  echo "Package python-base-app-0.2.9.tar.gz was found."
+  echo "Package python-base-app-0.2.13.tar.gz was found."
 fi
 
 if [ ! -f $TMP_DIR/some-flask-helpers-0.1.tar.gz ] ; then
@@ -182,19 +182,19 @@ chmod og-rwx /etc/little-brother/little-brother.config
 ${PIP3} --version
 ${PIP3} install wheel setuptools
 echo "Installing PIP packages..."
-echo "  * little-brother-0.3.10.tar.gz"
-echo "  * python-base-app-0.2.9.tar.gz"
+echo "  * little-brother-0.3.11.tar.gz"
+echo "  * python-base-app-0.2.13.tar.gz"
 echo "  * some-flask-helpers-0.1.tar.gz"
 # see https://stackoverflow.com/questions/19548957/can-i-force-pip-to-reinstall-the-current-version
 ${PIP3} install --upgrade --force-reinstall \
-     ${TMP_DIR}/little-brother-0.3.10.tar.gz\
-     ${TMP_DIR}/python-base-app-0.2.9.tar.gz\
+     ${TMP_DIR}/little-brother-0.3.11.tar.gz\
+     ${TMP_DIR}/python-base-app-0.2.13.tar.gz\
      ${TMP_DIR}/some-flask-helpers-0.1.tar.gz
 
 
-echo "Removing installation file ${TMP_DIR}/little-brother-0.3.10.tar.gz..."
-rm ${TMP_DIR}/little-brother-0.3.10.tar.gz
-echo "Removing installation file ${TMP_DIR}/python-base-app-0.2.9.tar.gz..."
-rm ${TMP_DIR}/python-base-app-0.2.9.tar.gz
+echo "Removing installation file ${TMP_DIR}/little-brother-0.3.11.tar.gz..."
+rm ${TMP_DIR}/little-brother-0.3.11.tar.gz
+echo "Removing installation file ${TMP_DIR}/python-base-app-0.2.13.tar.gz..."
+rm ${TMP_DIR}/python-base-app-0.2.13.tar.gz
 echo "Removing installation file ${TMP_DIR}/some-flask-helpers-0.1.tar.gz..."
 rm ${TMP_DIR}/some-flask-helpers-0.1.tar.gz
\ No newline at end of file
diff --git a/contrib/python_base_app b/contrib/python_base_app
index 27c8a9d..38e2ddd 160000
--- a/contrib/python_base_app
+++ b/contrib/python_base_app
@@ -1 +1 @@
-Subproject commit 27c8a9d185b39b8a7f599e617168ed100569439f
+Subproject commit 38e2ddd4f9b0e7adfa42d9ffa2fbf82284937cf2
diff --git a/etc/master.config b/etc/master.config
index 7cbf8d2..11789b0 100644
--- a/etc/master.config
+++ b/etc/master.config
@@ -50,6 +50,11 @@ scan_active=true
 # Default: 7
 #process_lookback_in_days = 14
 
+# Sets the number of days that entries of entities 'process_info', 'admin_event' and 'rule_override' will be kept
+# in the database. This number should always be at least one day larger than 'process_lookback_in_days'!
+# Default: 180
+#history_length_in_days = 30
+
 # Sets the number of future days that user play time configuration will be available in the frontend.
 # Default: 7
 #admin_lookahead_in_days = 14
diff --git a/little_brother/app.py b/little_brother/app.py
index 4791587..7b7e7a3 100644
--- a/little_brother/app.py
+++ b/little_brother/app.py
@@ -46,6 +46,7 @@
 PACKAGE_NAME = 'little_brother'
 
 DEFAULT_USER_HANDLER = unix_user_handler.HANDLER_NAME
+DEFAULT_CLEAN_HISTORY_INTERVAL = 24 * 60 * 60 # seconds
 
 
 class AppConfigModel(base_app.BaseAppConfigModel):
@@ -54,6 +55,7 @@ def __init__(self):
         super(AppConfigModel, self).__init__(APP_NAME)
 
         self.check_interval = base_app.DEFAULT_TASK_INTERVAL
+        self.clean_history_interval = DEFAULT_CLEAN_HISTORY_INTERVAL
 
 
 def get_argument_parser(p_app_name):
@@ -303,6 +305,14 @@ def prepare_services(self, p_full_startup=True):
                 p_interval=self._client_device_handler.check_interval)
             self.add_recurring_task(p_recurring_task=task)
 
+        if self.is_master():
+            task = base_app.RecurringTask(
+                p_name="app_control.clean_history",
+                p_handler_method=lambda: self._app_control.clean_history(),
+                p_interval=self._app_config.clean_history_interval)
+            self.add_recurring_task(p_recurring_task=task)
+
+
         if status_server_config.is_active():
             self._status_server = status_server.StatusServer(
                 p_config=self._config[status_server.SECTION_NAME],
diff --git a/little_brother/app_control.py b/little_brother/app_control.py
index 4861dc1..21bd89e 100644
--- a/little_brother/app_control.py
+++ b/little_brother/app_control.py
@@ -47,6 +47,7 @@
 DEFAULT_SCAN_ACTIVE = True
 DEFAULT_ADMIN_LOOKAHEAD_IN_DAYS = 7  # days
 DEFAULT_PROCESS_LOOKUP_IN_DAYS = 7  # days
+DEFAULT_HISTORY_LENGTH_IN_DAYS = 180  # days
 DEFAULT_MIN_ACTIVITY_DURATION = 60  # seconds
 DEFAULT_CHECK_INTERVAL = 5  # seconds
 DEFAULT_INDEX_REFRESH_INTERVAL = 60  # seconds
@@ -74,6 +75,7 @@ def __init__(self):
         super(AppControlConfigModel, self).__init__(p_section_name=SECTION_NAME)
 
         self.process_lookback_in_days = DEFAULT_PROCESS_LOOKUP_IN_DAYS
+        self.history_length_in_days = DEFAULT_HISTORY_LENGTH_IN_DAYS
         self.admin_lookahead_in_days = DEFAULT_ADMIN_LOOKAHEAD_IN_DAYS
         self.server_group = login_mapping.DEFAULT_SERVER_GROUP
         self.hostname = configuration.NONE_STRING
@@ -102,12 +104,21 @@ def node_type(self):
         return _("Master") if self.is_master else _("Slave")
 
     @property
-    def last_message_string(self):
+    def seconds_without_ping(self):
         if self.last_message is None:
+            return None
+
+        return (tools.get_current_time() - self.last_message).seconds
+
+    @property
+    def last_message_string(self):
+
+        some_seconds_without_ping = self.seconds_without_ping
+
+        if some_seconds_without_ping is None:
             return _("n/a")
 
-        seconds_without_ping = (tools.get_current_time() - self.last_message).seconds
-        return tools.get_duration_as_string(seconds_without_ping)
+        return tools.get_duration_as_string(some_seconds_without_ping)
 
 
     @property
@@ -465,6 +476,10 @@ def stop(self):
         if not self.is_master():
             self.send_events()
 
+    def clean_history(self):
+        self._persistence.delete_historic_entries(p_history_length_in_days=self._config.history_length_in_days)
+
+
     def queue_event(self, p_event, p_to_master=False, p_is_action=False):
 
         if p_is_action:
@@ -533,7 +548,14 @@ def handle_event_process_downtime(self, p_event):
 
     def handle_event_process_start(self, p_event):
 
-        pinfo, updated = self.get_process_handler(p_id=p_event.processhandler).handle_event_process_start(p_event)
+        process_handler = self.get_process_handler(p_id=p_event.processhandler)
+
+        if process_handler is None:
+            msg = "Received event for process handler of type id '{id}' which is not registered -> discarding event"
+            self._logger.warning(msg.format(id=p_event.processhandler))
+            return
+
+        pinfo, updated = process_handler.handle_event_process_start(p_event)
 
         if updated:
             if self._persistence is not None:
@@ -877,14 +899,14 @@ def pick_text_for_approaching_logout(self, p_rule_result_info):
         t = gettext.translation('messages', localedir=self._locale_dir,
                                 languages=[p_rule_result_info.locale], fallback=True)
 
-        if p_rule_result_info.approaching_logout_rules & rule_handler.RULE_TIME_PER_DAY:
-            return t.gettext(self.text_no_time_left_approaching).format(**p_rule_result_info.args)
+        if p_rule_result_info.approaching_logout_rules & rule_handler.RULE_ACTIVITY_DURATION:
+            return t.gettext(self.text_need_break_approaching).format(**p_rule_result_info.args)
 
         elif p_rule_result_info.approaching_logout_rules & rule_handler.RULE_TOO_LATE:
             return t.gettext(self.text_too_late_approaching).format(**p_rule_result_info.args)
 
-        elif p_rule_result_info.approaching_logout_rules & rule_handler.RULE_ACTIVITY_DURATION:
-            return t.gettext(self.text_need_break_approaching).format(**p_rule_result_info.args)
+        elif p_rule_result_info.approaching_logout_rules & rule_handler.RULE_TIME_PER_DAY:
+            return t.gettext(self.text_no_time_left_approaching).format(**p_rule_result_info.args)
 
         else:
             fmt = "pick_text_for_approaching_logout(): cannot derive text for rule result %d" % p_rule_result_info.approaching_logout_rules
diff --git a/little_brother/persistence.py b/little_brother/persistence.py
index 90e9f3e..c3b1e93 100644
--- a/little_brother/persistence.py
+++ b/little_brother/persistence.py
@@ -829,7 +829,7 @@ def update_rule_override(self, p_rule_override):
     def load_process_infos(self, p_lookback_in_days):
 
         with SessionContext(self) as session_context:
-            session_context = SessionContext(self)
+#            session_context = SessionContext(self)
             session = session_context.get_session()
             reference_time = datetime.datetime.now() + datetime.timedelta(days=-p_lookback_in_days)
 
@@ -846,6 +846,44 @@ def load_process_infos(self, p_lookback_in_days):
 
         return result
 
+    def delete_historic_entries(self, p_history_length_in_days):
+
+        msg = "Deleting historic entries older than {days} days..."
+        self._logger.info(msg.format(days=p_history_length_in_days))
+
+        with SessionContext(self) as session_context:
+            session = session_context.get_session()
+            reference_time = datetime.datetime.now() + datetime.timedelta(days=-p_history_length_in_days)
+            reference_date = reference_time.date()
+
+            result = session.query(RuleOverride).filter(RuleOverride.reference_date < reference_date).all()
+
+            msg = "Deleting {count} rule override entries..."
+            self._logger.info(msg.format(count=len(result)))
+
+            for override in result:
+                session.delete(override)
+
+            result = session.query(AdminEvent).filter(AdminEvent.event_time < reference_time).all()
+
+            msg = "Deleting {count} admin events..."
+            self._logger.info(msg.format(count=len(result)))
+
+            for event in result:
+                session.delete(event)
+
+            result = session.query(ProcessInfo).filter(ProcessInfo.start_time < reference_time).all()
+
+            msg = "Deleting {count} process infos..."
+            self._logger.info(msg.format(count=len(result)))
+
+            for pinfo in result:
+                session.delete(pinfo)
+
+            session.commit()
+
+
+
     def load_rule_overrides(self, p_lookback_in_days):
 
         session = self.get_session()
diff --git a/little_brother/settings.py b/little_brother/settings.py
index 5b7ff8a..b130c1b 100644
--- a/little_brother/settings.py
+++ b/little_brother/settings.py
@@ -18,7 +18,7 @@
 settings = {
     "name": "little-brother",
     "url": "https://github.com/marcus67/little_brother",
-    "version": "0.3.10",
+    "version": "0.3.11",
     "description": "Simple parental control application monitoring specific processes on Linux hosts "
                    "to monitor and limit the play time of (young) children.",
     "author": "Marcus Rickert",
diff --git a/little_brother/status_server.py b/little_brother/status_server.py
index 321f399..1ce8d69 100644
--- a/little_brother/status_server.py
+++ b/little_brother/status_server.py
@@ -15,6 +15,7 @@
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+import datetime
 import gettext
 import os
 
@@ -23,6 +24,7 @@
 import flask_babel
 import flask_login
 import flask_wtf
+import humanize
 
 import little_brother
 from some_flask_helpers import blueprint_adapter
@@ -170,6 +172,7 @@ def __init__(self,
         self._app.jinja_env.filters['format_babel_date'] = self.format_babel_date
         self._app.jinja_env.filters['format_text_array'] = self.format_text_array
         self._app.jinja_env.filters['invert'] = self.invert
+        self._app.jinja_env.filters['seconds_as_humanized_duration'] = self.format_seconds_as_humanized_duration
         self._app.jinja_env.filters['_base'] = self._base_gettext
 
         self._babel = flask_babel.Babel(self._app)
@@ -236,6 +239,21 @@ def format_time(self, value):
         else:
             return value.strftime(self._config.time_format)
 
+    def format_seconds_as_humanized_duration(self, seconds):
+
+        if seconds is None:
+            return _("n/a")
+
+        try:
+            # trying to activate the localization for a non-existing locale (including 'en'!) triggers an exception
+            if self._locale_helper.locale is not None:
+                humanize.i18n.activate(self._locale_helper.locale)
+
+        except Exception:
+            humanize.i18n.deactivate()
+
+        return humanize.naturaldelta(datetime.timedelta(seconds=seconds))
+
     @staticmethod
     def format_seconds(value):
 
diff --git a/little_brother/templates/topology.template.html b/little_brother/templates/topology.template.html
index 868faa8..4b010ee 100644
--- a/little_brother/templates/topology.template.html
+++ b/little_brother/templates/topology.template.html
@@ -66,7 +66,7 @@
             <DIV CLASS="col-xs-2 localetext {{ info.version_class }}">{{ info.version_string }}</DIV>
             <DIV CLASS="col-xs-2 localetext">{{ info.client_stats.revision }}</DIV>
             <DIV CLASS="col-xs-2 localetext">{{ info.client_stats.python_version }}</DIV>
-            <DIV CLASS="col-xs-2 localetext {{ info.last_message_class}}">{{ info.last_message_string }}</DIV>
+            <DIV CLASS="col-xs-2 localetext {{ info.last_message_class}}">{{ info.seconds_without_ping | seconds_as_humanized_duration }}</DIV>
         </DIV>
         {% endfor %}
     </DIV>
diff --git a/requirements.txt b/requirements.txt
index 1a5d939..a7fa08d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,3 +12,4 @@ Flask-WTF>=0.14.3
 selenium>=3.141.0
 urllib3>=1.26.2
 prometheus_client>=0.9.0
+humanize>=3.2.0