Quote From The Google Play Store
“Battery Doctor is a tool that helps you save battery power and tells you approximately how much life your battery has left ( So does your phone !!!). By using many different features, it lets you improve (in some cases) ( yes they actually wrote this ) its duration.
The method for doing this consists of a program based on three charges that might be able to give your battery some extra life. (note the “might be able) The most important feature for improving your battery’s life is the tool that deletes processes, which is included on Battery Doctor”( No its not and modern smartphones do this
No …..apart from not needing this on smartphones ,(you will probably get better luck waiving a dead chicken over your smartphone ) the develope and an associated company appear to be in a bit of trouble and there are ads