Same problem - Is this because the version of Deskscapes that I purchased is the 11 Beta?
It is not going away. I followed your link and the command prompt does not work for version 11 either.
If 'same problem' means you tried what is here and it still does it:
I am near certain you have an over-active AV app that is nuking the license.sig file for each. You can watch that in action if you like, Fences example.
C:\ProgramData\Stardock\Fences4 (note that is ProgramData, not Program Files - you will need to show hidden folders if you don't see it - a google search away).
If Fences is asking for activation, no license.sig will be there. Keep it up so you can see both, the activation window and that folder. After activation, it will create a license.sig. At some point, it will be gone if my theory is correct, that your AV app nuked it - you can check you logs to confirm it.
Example of activation process:
Stardock Support Manager