Actually I hope to have solved the problem.
What I did was a few hectic import/exports of the plug files between the computer (I did get the error message you are referring to, maybe not the same code).
Then I erased a couple of files on new computer (I am not sure I am allowed to tell which) and lo and behold, on my new computer the licens is active and it says it expires "never".
I just hope it stays that way, he,he,he
Ales