I think it would be way to go Home → Pro if you enter Pro trial key. But since you can’t get it other than with new installation of avast! Pro it’s only possible other way around. As far as i know you can just enter new key for avast! Pro (if you buy one) into avast! Home and will also upgrade to Pro version. Vlk or someone from ALWIL could’t confirm this for sure if it’s true or not…