Customize monetization for an Android app + server PHP script

Hello, I'm planning to launch an app based on the "dating app" PHP script+android app by qascript. Please check google to have full specs as I'm not sure if I can post it all here. The app has some functionalities that work with in-app credits. I'm not satisfied with the monetization plan and the original programmer has no time to produce the custom version that I want. Globally, the changes rather small patching jobs since the app and script are both tested and fully functionning. What is already there : * Buy credits for $$ * Get credits for email invite * Some functions are locked behind a credit wall What is needed : Simple modifications: * Remove credits for email invite * Modify credit for $$ * Modify already built-in rewards Bigger overhaul: * Add watch rewaded videos button to get credits with cooldown * Lock some functionalities behind a credit wall * Rearrange the app menu more logically to fit the new plan (* Add Gmail login) -> Also: * produce a (very simple) documentation with file name + lines edited. I will provide the vanilla source code of the PHP script + the android app as well as my desired monetization plan so you can clearly and easily work. I don't have any strict time for launch so lower prices for longer development are welcome as long as the timeframe is agreed upon beforehand correctly. After this job, possibility to keep working together to fix some minor glitches, migrate to firebase and work with the iOS version. This is a personal project so provided that I get a satisfying offer there's little change that it will be cancelled. Thanks for reading this! CM