I have tried to stop popups to renew my trial Pro version and support phone conversation was unsuccessful.
Did you actually install avast Pro as a trial version, or is there another reason for this ?
If you installed it legitimately then it isn’t unusual to have it pop-up purchase reminders, but not renew pop-up for the Pro trial version. There are no renewal notices for trial versions, so there is more to this than actually stated.
If you can attach a screenshot for the renewal pop-up.