Author here. This needs to be prominent. Paying for subscription at least once prevents subdomain from ever being put back in the available pool. If you subscribe but then cancel your subscription on Stripe portal, it'll run until the end of current subscription period. After that, the system will stop fetching new hoots, but it'll continue to serve the last state of RSS feed and the subdomain will remain in your possession. I'm not evil and not about to break the links for everyone :) Yeah, this really needs to be put somewhere prominent.
App has no need of seeing your secret gists, but sadly Github oauth app scopes aren't granular enough. I'll only be too happy to not take on any more responsibility than I have to.