Surely the tons of people who use the software have more authority on the matter than someone who doesn’t. Besides, you shouldn’t need a trusted authority to tell you that online features require an internet connection.

The wording is clear, Affinity is free, the license is perpetual, but you need to have an internet connection to get updates

Yeah, other than directly contacting Affinity, we won't know which case is correct. However, the one thing we can say for certain is that the credential refresh timer is not on the scale of minutes. From anecdotes in the official forums, it's pretty clear that it is at least a 30 day refresh timer, though some people report it never needing to be refreshed