For this, you have to insert the Webroot Installation CD in your Computer’s CD Drive and it will autoplay its Installation Wizard. Now you should follow the Instructions to complete the Installation process. Then you have to launch the Installed application. Here Webroot Login in your Account. After this, just locate the “Gear” icon and click on it. On the window, just go to the “Activate a New Keycode” section and here enter your “Product Activation Key”. At last, click on the Activate button.
If you are still facing the issue then you can visit to the official site of Webroot antivirus through Webroot.com/safe.