For correct work of application:
1) Open “Settings ⟶ Battery ⟶ Power saving management”.
1.1) Turn OFF option “Ultra-long standby during sleep”.
1.2) Turn OFF option “Lock-screen cleanup”.
1.3) Turn ON option “App protection ⟶ Prof Reminder”.
1.4) Turn OFF both options in “Align wakeup”.
1.5) Turn OFF option “Battery assistant”.
2) Start dialer app and type *#*#46360000#*#*, then turn OFF option “Enable background resource control”.
3) Turn ON option “Phone Manager ⟶ Security and privacy ⟶ Manage auto launch ⟶ Prof Reminder”.