My account has been downgraded from Pro to Free. Sync with Google calendar not working.

1.I renewed my account, but tasks has not been syncing.
2.I unlink Doit from GCalendar and unauthorized doit.Im from Google account
3. Setup new Doit → GCalendar connection takes no effect
4. I updated some tasks and created some new tasks but it aslo takes no effect

If it still not working I need to refund my money