1. Right-click the Avast icon in your system tray and select Subscription information.
2. On the My licenses screen, click Enter a valid activation code.
3. Enter your activation code into the text box and click Enter:
4. Check your license details for the entered activation code. If you have an activation code for interchangeable products, you can click on a listed item and select an alternative license from the drop-down menu. Then click Continue to return to the My licenses screen.
5. Your Avast Internet Security license is now activated. The expiration date of your license appears under Licenses on this PC.
You can activate your license on the number of PCs you specify when making the purchase. The number of PCs in your license is specified in your order confirmation email.