Would be a worthwhile implementation pattern, though not sure Id want nodeless or any similar payment processor to have account info for contact (email, nostr, whatever), or the subscription details itself.

Better way to implement is as service that people can run on a vps so they maintain that data on their own and only call nodeless for generating invoice and relying on webhook. And then have daily check of accounts with subscription expiring soon and start notifying.

Would be a good hackathon project.

If I built something like this Id probably leverage AWS just for more expedient buildout and lower initial costs.