Hello contactaxiom,
Have you tried to run GrimeFighter yet? When you go to your MyAvast account you should enable one of the licenses, especially if it shows 3 valid licenses there. Then you will be able to reboot into Linux and run GrimeFighter by selecting "optimize my PC"
Maybe, could you send a screenshot of your MyAvast account and the email from which you purchased GrimeFighter? If you include that in a Support ticket and post the ticket number here I will make sure it is handled asap.
Many thanks,
Davidek