I like the model of charging for open source software, perhaps with slightly better support in return. It doesn't have to be as serious as the RedHat model either.

Something like how Bitwarden does it seems reasonable to me. You can run your own server if you buy a license, or you could just take their source and comment out the license check, but the license is so cheap so why bother?

I do wish they had a lifetime license though. I hate subscriptions.