Yes its one time for android, if you’re earning money with ads or purchases, google will take 1/3 of that amount, then you will have to figure out taxes on your own and there’s also some special policies for selling online goods in India, but if you’re just making apps - its one time fee to be able to upload them to google play store, or you can just distribute with froid/github for free, which is a great route as well
That’s a con and a pro of decentralized net: if you don’t like the owner, pick another instance or create your own and be the king. Bad news is, every instance is controlled by couple regular folks who’re not responsible financially so they can imply their own rules and post and ban whatever they want.
Like the jungle: you gotta learn to survive and avoid the monkeys with rabies.