The MaxMon app is split into a configuration portion (the app itself) and a long-running background service that actually scans the sensors, schedules tasks, detects alert conditions, executes corresponding actions and sends routine and alert email and text (SMS) reports.

THIS BACKGROUND SERVICE MUST BE RUNNING
FOR MAXMON TO DO ANYTHING USEFUL!

You don't want to leave MaxMon behind at a remote monitored property and drive home, only to realise you forgot to start the background service. So get in the habit of leaving the service running by 'arming' the app (by clicking one of the buttons under the mouse hole on the MaxMon app home screen - see Q: how do I arm/disarm the MaxMon app?). Once the service is running you can close the MaxMon app. A small MaxMon icon in the notification area at the top of the phone's screen will confirm that the background service is running.