Sorry to hear that...
Knock on wood - my free account still works!
When I created it 4 years ago, I named it 'homeassistant' - maybe this has immunized my account from expiring .. 
As I posted above, Tuya recently cut off the free accounts for Homey new users, but for now the Home Assistant integration is still free. However, as far as I know, Home Assistant uses other authentication methods; they worked together with Tuya on this integration.
