Best answer by shorTcircuiT
Since you had a Best Buy license, and now purchased a new key code that is supported directly through Webroot, you will need to uninstall the Best Buy version and re-install using a fresh download. Use the download link below in my signature area, but NOT the Best Buy link.
While the Best Buy version is essentially identical in most ways, it DOES have a separate Key Code Database, and the key codes cannot be interchanged in the same manner.