AVG license key not working is a common error that appears in all versions of AVG, free, trial and paid. You can resolve this error using the AVG clear and remover tool. Just follow the steps given below:
•Download the AVG remover tool using the link from the website.
•Run the tool on your computer and follow the instructions to uninstall AVG.
•Once the program is uninstalled your computer will restart automatically.
•Go to the drive and delete all supported products and AVG files.
When this is done you can visit the AVG website or Avg support for assistance in reinstalling AVG antivirus.