diff --git a/app/src/main/java/com/wesaphzt/privatelock/fragments/FragmentSettings.java b/app/src/main/java/com/wesaphzt/privatelock/fragments/FragmentSettings.java
index 5456de0..5289f55 100644
--- a/app/src/main/java/com/wesaphzt/privatelock/fragments/FragmentSettings.java
+++ b/app/src/main/java/com/wesaphzt/privatelock/fragments/FragmentSettings.java
@@ -7,7 +7,9 @@ import androidx.annotation.Nullable;
 
 import android.view.Menu;
 import android.view.View;
+import android.widget.Toast;
 
+import androidx.preference.CheckBoxPreference;
 import androidx.preference.PreferenceFragmentCompat;
 import androidx.preference.PreferenceManager;
 
@@ -15,17 +17,26 @@ import com.wesaphzt.privatelock.R;
 
 public class FragmentSettings extends PreferenceFragmentCompat {
 
-    private SharedPreferences prefs;
+    private Context context;
+
+    private CheckBoxPreference cbRunConstant;
+
+    private SharedPreferences sharedPreferences;
+    private SharedPreferences.OnSharedPreferenceChangeListener sharedPreferenceChangeListener;
 
     @Override
     public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
         addPreferencesFromResource(R.xml.preferences);
 
         setHasOptionsMenu(true);
-        Context context = getContext();
+        context = getContext();
+
+        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
 
         //this static call will reset default values only on the first read
         PreferenceManager.setDefaultValues(context, R.xml.preferences, false);
+
+        cbRunConstant = (CheckBoxPreference) findPreference("RUN_CONSTANT");
     }
 
     @Override
@@ -33,6 +44,24 @@ public class FragmentSettings extends PreferenceFragmentCompat {
         super.onCreate(savedInstanceState);
     }
 
+    @Override
+    public void onResume() {
+        super.onResume();
+        sharedPreferences.registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        sharedPreferences.unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
+    }
+
+    @Override
+    public void onPause() {
+        super.onPause();
+        sharedPreferences.unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
+    }
+
     @Override
     public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);
@@ -41,6 +70,16 @@ public class FragmentSettings extends PreferenceFragmentCompat {
 
         //bg color
         view.setBackgroundColor(getResources().getColor(R.color.white));
+
+        sharedPreferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener() {
+            @Override
+            public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
+                if(key.equals("RUN_CONSTANT") && cbRunConstant.isChecked()) {
+                    Toast.makeText(context, getString(R.string.settings_restart_service_toast), Toast.LENGTH_LONG).show();
+                }
+            }
+        };
+        sharedPreferences.registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
     }
 
     @Override
diff --git a/app/src/main/java/com/wesaphzt/privatelock/receivers/BootReceiver.java b/app/src/main/java/com/wesaphzt/privatelock/receivers/BootReceiver.java
index 7c27e60..115483a 100644
--- a/app/src/main/java/com/wesaphzt/privatelock/receivers/BootReceiver.java
+++ b/app/src/main/java/com/wesaphzt/privatelock/receivers/BootReceiver.java
@@ -16,7 +16,7 @@ public class BootReceiver extends BroadcastReceiver {
     public void onReceive(Context context, Intent intent) {
 
         if (intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
-            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);;
+            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
             if(prefs.getBoolean("START_ON_BOOT", false)) {
                 Intent i = new Intent(context, LockService.class);
 
diff --git a/app/src/main/java/com/wesaphzt/privatelock/service/LockService.java b/app/src/main/java/com/wesaphzt/privatelock/service/LockService.java
index 7dc19eb..e68c528 100644
--- a/app/src/main/java/com/wesaphzt/privatelock/service/LockService.java
+++ b/app/src/main/java/com/wesaphzt/privatelock/service/LockService.java
@@ -83,18 +83,18 @@ public class LockService extends JobIntentService {
             String action = intent.getAction();
 
             LockWidgetProvider lockWidgetProvider = new LockWidgetProvider();
+            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
 
             switch (action) {
-
                 case ACTION_START_FOREGROUND_SERVICE:
-                    presenceReceiver = new PresenceReceiver();
-
-                    IntentFilter intentFilter = new IntentFilter(Intent.ACTION_USER_PRESENT);
-                    intentFilter.addAction(Intent.ACTION_SCREEN_OFF);
-                    registerReceiver(presenceReceiver, intentFilter);
+                    if(! prefs.getBoolean("RUN_CONSTANT", false)) {
+                        presenceReceiver = new PresenceReceiver();
 
+                        IntentFilter intentFilter = new IntentFilter(Intent.ACTION_USER_PRESENT);
+                        intentFilter.addAction(Intent.ACTION_SCREEN_OFF);
+                        registerReceiver(presenceReceiver, intentFilter);
+                    }
                     //------------------------------------------------------------------------------------------
-                    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
                     try {
                         SENSITIVITY = prefs.getInt(MainActivity.PREFS_THRESHOLD, DEFAULT_SENSITIVITY);
                     } catch (Exception e) {
@@ -134,7 +134,9 @@ public class LockService extends JobIntentService {
 
                 case ACTION_STOP_FOREGROUND_SERVICE:
                     try {
-                        unregisterReceiver(presenceReceiver);
+                        if(! prefs.getBoolean("RUN_CONSTANT", false)) {
+                            unregisterReceiver(presenceReceiver);
+                        }
                         mSensorManager.unregisterListener(activeListener);
 
                         disabled = true;
@@ -145,6 +147,9 @@ public class LockService extends JobIntentService {
                             PauseReceiver.isRunning = false;
                         }
                     } catch (Exception e) {
+                        if(! prefs.getBoolean("RUN_CONSTANT", false)) {
+                            unregisterReceiver(presenceReceiver);
+                        }
                         disabled = true;
                         mInitialized = false;
 
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 93248c1..ca2b24a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -62,6 +62,9 @@
 
     <string name="about_bug_report_image_desc">Bug report image</string>
 
+    <!--message-->
+    <string name="settings_restart_service_toast">If service is running, restart for setting to take effect.</string>
+
     <!--donate-->
     <string name="donate_bitcoin_image_desc">Bitcoin image</string>
     <string name="donate_litecoin_image_desc">Litecoin image</string>
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 4ef18b6..c60b8a6 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -2,20 +2,25 @@
 <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
     <PreferenceCategory
         android:title="Lock Service">
+
+        <CheckBoxPreference
+            android:defaultValue="false"
+            android:key="START_ON_BOOT"
+            android:title="System start" />
+
+        <CheckBoxPreference
+            android:defaultValue="false"
+            android:key="RUN_CONSTANT"
+            android:title="Run service when locked"
+            android:summary="Run service all the time, even when the screen is off, to be able to force PIN entry at any time."/>
+
         <ListPreference
             android:defaultValue="1"
             android:entries="@array/array_pause_minutes"
             android:entryValues="@array/array_pause_minutes_vals"
             android:key="PAUSE_TIME"
             android:summary="%s"
-            android:title="Pause time" />
-    </PreferenceCategory>
+            android:title="Pause length" />
 
-    <PreferenceCategory
-        android:title="Application">
-        <CheckBoxPreference
-            android:defaultValue="false"
-            android:key="START_ON_BOOT"
-            android:title="System start" />
     </PreferenceCategory>
 </PreferenceScreen>
\ No newline at end of file