Disclamer: This article has been copied from ASUS support site, because the articles are sometimes deleted (Source link : https://www.asus.com/support/FAQ/1013752/)
ZenFone Series - How to give apps start-up privileges or disable start-up apps to extend battery life and extend more system RAM.
Depending on the amount of apps you have available. Our Asus ZenFone Series comes with an Auto-Start Manager application that you can use to choose which apps you want to enable or disable on system start up.
In the Auto-Start Manager, you can Allow or Deny Apps that you either downloaded or some of the apps that were preloaded onto the device from factory.
To open Auto-Start Manager tap on APPS then tap on the Auto-Start Manager app. Alternatively, use the quick swipe down quick settings (Swipe twice from top to bottom) while on home screen to show the quick settings.
-Auto-Start Manager from quick swipe.
From the Home screen, swipe once from top to bottom to open up the quick settings menu. Swipe from top to bottom again to open up the quick settings apps. Then tap on the quick setting app Auto-Start Manager.
Auto-Start Manager from the app.
From the HOME screen, tap on APPS.
From the APPS screen, tap on the AUTO-START MANAGER icon.
You will first see the DOWNLOADED apps field you can toggle apps to ALLOW or DENY with a tap in this field.
Choose the APPS accordingly to your preference to which you want to start up on first boot which also gives it full start up privilege access in RAM on the OS level.
Tapping on the PRELOADED option will show the PRELOADED apps. Choose with you want to toggle privileges by tapping on the applicable app to ALLOW or DENY start-up access in the OS.
Finally, tapping on ADVANCE options/settings (The three dots on the upper right hand corner) will toggle advance selections for the AUTO-START MANAGER app. Selections to choose are - SORT BY, SHOW ALL APPS, ENABLE NOTIFICATIONS, RESTORE TO INITIAL CONFIGURATION, NOTICE, FEEDBACK & HELP.
VERY IMPORTANT: Restart your device after going through all the step (in order to fixed to previous alarms)