i purchased the annual subscription of Sketchbook Pro for 29.95. I had to login to Autodesk and MS Store so I don't know who to contact. There is no intuitive way to download the app. I am using the MS Surface Pro 4.
If you're trying to use a trial version that you want to 'upgrade' to full subscription version, best thing to do is to uninstall the trial, and download from the link you should have received in your purchase email.
