I want to avoid running into the issue of uncontrollable bills.
Issues like this https://trufflesecurity.com/blog/google-api-keys-werent-secrets-but-then-gemini-changed-the-rules
the best idea I can suggest is to set up a virtual debit/credit card, if your bank permits it - for example, I have one which I keep at a level that's enough to pay for my monthly patreons, etc, but which will not pay when it hits zero. Then I don't have to worry (that much) about, eg, a data breach.