If you log into your account through your laptop, on the right hand side under My Profile, select Sky Sports and Movies. This should hopefully show the two devices that you have registered. As you already have one change remaining this month, you can remove either both of these devices or just the one. Then re-register the laptop now in December then in January the changes will be updated.
Hope that makes sense, if you do have any issues with the registration or the changes, by all means let us know.