Why does the Android OS keep on closing running background apps?

So android is trying to be as optimized as an os can be and for this it tries to keep a certain amount of ram for smooth experience of the os.But to do so it would need to suspend apps to make that free space and hence it keeps killing app using last used first kill.Also this automatically saves battery as there are less applications hogging the cpu of your phone there by keeping it idle for longer and hence saving battery.

Android is built in such a way that it 'suspends' any task that runs in the background i.e. if I am using Whatsapp and then I shift over to Chrome, Whatsapp will be held in a suspended state which is resumed, once you return to the main app. I haven't used everycover or battery doctor or power toggles so I have no idea about how those apps behave. Usually when an app runs persistently in the background, a persistent non-dismissable notification pops in the notification shade so as to keep the app in the memory and prevent Android from suspending it. Battery doctors and other apps which 'claim' to increase battery life rarely do and consume a major portion of battery themselves. I'd recommend you to ditch it in favour of Greenify. Also I would recommend you to check out Gravity Screen. I have a feeling that a task killer of some sorts is killing those apps. I may be wrong though. I would like to ask you to head over to the settings of the respective apps and switch on persistent notification option (if they have one). If it still doesn't, you can hunt the Play store for alternatives. Hope this helps!

There is no way to force Andriod OS to keep running a background application. It totally depends on the code of the app you are using. That is a sign a bad code by the App. A user should never have to bother with this and Android provides means so that an App can save their state and restore it later on. Send a feedback report to the developer.

Please do try out du battery saver pro..that's pretty good..and yeah download any third party app and add whatever app you want not to shutdown to the ignore list.. preferably download clean master..

It is not only Android, but all Mobile Operating Systems optimize RAM usage by killing background apps.This is done so that the foreground app can be given top priority. It ensures smooth functioning of the current app and reduces load on the system.To overcome this situation, increasing RAM is an option but you cannot do it at the end-user level. Hence, manufacturers are now constantly increasing RAM on their devices and you can see new phones coming out with 3GB or even 4GB RAM now.

Give administrative access to both the apps, then it will never suspend those apps