It seems I was a bit too fast to say there is no final XP version. Apparently support for XP has stopped with this last version… Though it still is rather recent (14 July 2014), I’m afraid you may have a problem with WL6 on XP when your license on the USB-key changes to a different version number. Although it could be that this final version has a special way to foresee higher version licenses. Maybe PG can shed some more light on it?