First of all, if you want to do android apps' modding, you need to learn smali, this is the main thing on apps' modding, and the only similar thing that could exist between a game and a app, is that the specific offset might be stored in the lib, if im not wrong, Kinemaster has premium stored in its lib, even if it can be modded directly from smali, secondly, you need to memorize, some keywords, like "ispremium", "haspremium", "is_vip", "subscriptionbought" etc. Memorizing keywords, will give a higher percentage of succesful work, instead of struggling 20 mins to find a keyword. ID method, exists too, like getting the id of a keyword from the resources of the apk, which you cant usually find it in apk's dexes, but this is usually used for more advanced apk's, so i suggest you to start with basic ones. There are surely more tools that could help you to finish faster the work, but until then, do what i said, and about smali tutorials, they exist on this site, google, or YouTube, so its not a limited resource to say you can find what you want to search.
