Access this feature at: Menu ▸ Account

The Account screen allows you to login to an Avast Account, or create one by clicking Create an account now in the bottom right corner. When you register Avast Free Antivirus an Avast Account is created automatically. Account registration is optional for users of paid editions. The Avast Account is a self-service web portal that enables you to manage the following:

If you want to connect your computer to a different Avast Account, simply log out and then login to the other account.