I have tried the "accepted answer" suggestion twice after restarts and on my mac I cannot even get to point 3, let alone to 4. on "Activation". There is no such clickable 'license' settings as the help answer suggest.
Bad advice. Even the Matworks staff does not know any viable solution. Bad situation all around ...
Here is my advice and answer:
uninstall the worrisome version of Matlab and install a new version. That worked like a charm for me and I am free from licence hassels, hopefully for many years now.