Your my.avast.com portal says you don’t have any licenses, because it thinks your ‘old PC’ is still running (not your laptop) so you’ll need to delete that system from your my.avast.com portal to get use of the license ‘old PC’ is using and now assigned to it.

Once you delete the ‘old PC’ license you will have a spare license for use. This should work unless I’ve grossly got it all wrong.