@lucarcari
Having changed computer has probably messed things up.
Assuming you no longer have access to the license file you saved onto your previous computer, or the email which sent it to you, have you tried the SketchUcation My Licenses page, whilst logged in as the user who bought the license ?
https://sketchucation.com/webshop/my-licences.php
This allows you to deactivate any 'old' licenses, download a copy so you can activate a new one etc...