It's just an idea, but what if itch.io can provide us some API for my web game, so that people that trying to play my game would have to enter some secret code that is provided by itch.io system. Or maybe get some credential from their user's login info / session, so only people that already buy my game can play the game. Or provide us with some API that we can use whenever we are initiating some function via JSON format or something. Because I try to switch to windows platform for my game, and the engagement rate go down pretty far. But if I stick to the web platform, I don't how to monetize it unless I created my own web service API for an in-apps purchase system.
Thanks in advance.