There should also have been a number of other pop-ups and a change in the avast tray icon as when your registration expired you can’t get virus definition updates.

After a short time frame avast would be alerting about that on startup, in the avastUI (not secured) etc. and the tray with a yellow triangle with ! over the avast icon.

Not to mention the Windows Security/Action Center would also have been popping up that avast is out of date after 7 days.

So I’m at a loss as to why you weren’t seeing those either.

Do you happen to have avast set on Silent Gaming Mode in the avastUI, Settings, Silent/Gaming Mode ?