It cointains a hibernate function to maximize the battery charge. And it works pretty well.
Ranked in these QuestionsQuestion Ranking
Pro The selection of the app to be suspended is smart
Everything continues to work.
Pro Can hybernate / suspend permanently other apps
The battery charge benefits a lot.
Con Almost zero benefit
Clean Master and similar apps were popular when Android still had memory problems (more than 2 years ago). Since then, virtually everything Clean Master does has been added into the base Android code. You can clear RAM through the settings on your phone if you feel the need, however Android is now smart enough to remove apps from RAM when needed (when more RAM is required by other more recently used apps, or when the background apps are taking up too many resources).
If anything, Clean Master takes more battery because it's constantly scanning, and any app it removes from RAM will have to be re-loaded in the future which defeats the purpose of more RAM (not to mention re-starting an app taxes the processor, draining battery faster). As the saying goes, "free RAM is wasted RAM".