Web Monetization refers to this new technology
https://webmonetization.org/docs/getting-started
https://webmonetization.org/docs/api
More info on https://coil.com/
Generally you want to detect if WM is supported and paying, then unlock features / disable ads if that is the case. It could be you get unlimited lives if WM is detected, you get 1x special key a day, extra special chests spawn in the world if WM is enabled, that kind of thing.