@merkir I am trying to find a copy of the licence key (for some reason I deleted my purchase one at some point without realising it).
This post is to flag up that:
The above method isn't working on DriveThru all you get is the PDF of the instructions to download. If you follow the basket route the site will want full price. In reality, given the use I get out of the app I'm cool with doing that if it becomes necessary.
I'm going to see what DriveThru do and will post a response.