So after a period of sickness I relaunched Cubase Artist 12 today (was working fine a few weeks ago) and… “no valid license found”. I tried everything but even in activation manager, download manager: nothing. I purchased Cubase11 (with promo to auto-update to 12) a year or so ago. And when I try to enter download access code I get the message that it’s already been consumed by another user. huh? Anyone else had this issue?
Everybody that tries to use the one time code a second time.
Download Access Code can be used once.
Download Access Codes work only a single time. So you are the one that consumed the code. 
That does not restrict from downloading the software, though. You just don’t have to enter that code.
If “no valid license” pops up it is usually best to restart the computer.