How can I keep an app always running? I have started using CM Security on my new phone which runs Android 6.0. I use the Applock feature, but the problem is it doesn't work because... just as I kill the window from my recent apps, CM Security also stops running in the background and as a result the password protection doesn't work. 

So I was looking for a way to keep the app always running on the background.

P.S: My phone is not rooted.
The app Wake Lock Revamp - Power Manager 
helps to keep apps running in the background.