To activate Avast Internet security, first you would need to have the latest version of Avast Internet Security 2019 (recommended) or 2018 installed on your Windows PC.
Then please follow below steps:
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- Type or paste 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.
Your Avast Internet Security license is now activated. The expiration date of your license appears under Licenses on this PC.
Please feel free to contact us if there is anything we can help you with.