What happens if a payment fails?
A new subscription gets no key until the first payment succeeds. If a renewal fails, your key keeps working for 5 days while we email you, then it is paused, and it resumes automatically once the payment is settled.
If a payment is disputed or reversed, the key may be paused straight away while the matter is reviewed.
A paused key is refused with key_paused (HTTP 403), and the console says why it is paused.