I have exactly the same problem - every time I start off the Laptop, and click on Start. I get prompted to register it again.
I have uninstalled, reinstalled, I have put the registration code and I have used the "sign into your account" method - I get told "Thank you for activating" and then, next time the laptop is started up, the same thing happens.
It has no gotten worse as ShadowFX has decided to get in on the act and also demand reactivation....
I will follow this thread and see if you guys come up with a resolution - but as with the latest Win10 I read that other programs from Objectdesktop are not always working, I am considering to just let the subscription expire as I do not get any value from it.
Oh and please - no "can you try this" - I have already tried it and it did not work ;-(
PS - If you need some more info to go on - I have the 1809 Win build (updated to 17763.55) and, if it makes any difference, I have two Windows 10 installs on the same computer - one for office and one for other stuff. I use the same computer name in both installs, as, for all intends and purposes, it is ONE Install on one computer (I cannot use them both at the same time - think two different software configurations).
Hope this helps....