What does don’t keep activities mean?

Basically in layman’s terms Don’t keep activities is a function whose job is to kill every app as soon as the user comes out of it . This means that the Android has to load the app’s resources every time the user opens as it does not have the cached data or memory of that specific app to perform that task.

How to access developer options in Android

Exemptions. Preloaded system apps and cloud messaging services are typically exempted from App Standby and Doze by default . App developers can use Intents to apply these settings to their apps. Users can exempt apps from App Standby and Doze power-saving modes in the Settings menu.

The power-management features fall into two categories: App standby buckets. The system limits apps’ access to device resources like the CPU or battery, based on the user’s usage patterns . This is a new feature for Android 9. Battery saver improvements.

Active: App is currently being used or was very recently used. Working set: App is in regular use . Frequent: App is often used, but not every day.

App Standby puts apps into “standby” mode when you aren’t actively using them. In general, if you never launch an app, Android will put it into standby mode. However, apps that display notifications on the notification tray or on the lock screen won’t go into standby mode.