⏰ In a nutshell,
It means to NOT remove Alarmy from the recent app list, which is the screen you see by double tapping home button or swiping up home bar at the bottom of the screen.
⏰ To elaborate,
While using iPhone or iPad, you probably would have seen this screen in order to go back to the app you were using before.
You can see this screen by
- (if there's a physical home button) double tapping the home button
- or (if you don't have a home button) swiping up the home bar which is a black bar at the very bottom of the whole screen.
When you swipe up an app from this screen, that app is completely terminated; this action is called "removing app from the background." Once an app is terminated this way, the app's activity is very limited.
Thus, "leaving/maintaining Alarmy in the background" means the opposite: NOT removing Alarmy from the recent app list and leaving it on the list.
⏰ Keep this in mind
Do you want to know why and when you need to leave Alarmy in the background?
Check this article about how to make sure Alarmy rings!