You can use your Windows 10 key to activate Windows 11. We've also seen reports that you can use your Windows 7 or Windows 8.1 key to activate Windows 11, but there's no guarantee this will work. However, there's no harm in trying to use these keys if you have them. Alternatively, you can activate Windows 10 with a Windows 7 or Windows 8.1 key and then use the Windows 11 Installation Assistant to upgrade to an activated copy of Windows 11.