You don't need any subscription to run the code! By default, none of the enterprise code runs (and it can all be completely removed and the app will work as expected). Fully FOSS version here: https://github.com/onyx-dot-app/onyx-foss.
As I see it has whitelisting and enterprise integrations.. as for the OS version maybe you need to roll your own. This is a usual monetization method though.
