The offline app licensing system is explicitly designed to only require refreshing the status regularly, each successful refresh will keep the state for six months even it it fail to refresh during that period. After the six months there comes the one month grace period (basically reminding the user to get online or contact their IT) where there's a warning banner but it still work. After the grace period it will disable saving.

The super-complicated app that fail when an online service fail in Microsoft's offering is Notepad, at least in one botched update where failed Copilot apparently crash Notepad entirely instead of letting it run without Copilot.