Here's my FAQ regarding the shift to the paid version: https://phanes.itch.io/ruin-me/devlog/858279/paid-version-faq Buying on Itch will get you all future updates. Patrons just get the next version early while it's still in active development (and also get a key for the main Itch download).
You can pay once to get every future update, or become a patron to get early preview builds. I think this is very reasonable, especially since there's a free hours-long demo so you know whether or not you want to commit.