after upgrading my pc with a new disk, can i still use it or do i have webroot to a reset of the licence?
You can do it. The limitation is on how many computers it's installed and running on. Now it's not running on the "old computer" (Old HDD), so you can put it on the new one.
And if you do have any issues just contact WSA support and they will be happy to help you! https://www.webrootanywhere.com/servicewelcome.asp? TH