Installed Windows 10 and after about 30 days, a message appears about activating Windows. How to fix it?

Question

Windows

Installed Windows 10 and after about 30 days, a message appears about activating Windows. How to fix it. There was no key, initially there was a seven, but then it was updated to 10k.

Answer 1

I don’t know about others, but I just took it and found the license key and that’s it. I still use it.
Lots of keys on the internet

Answer 2

Until January 2018, different rules for key recovery were in effect. Previously, the code on the seven could be used on the ten. Experienced users simply switched through an open loyalty program. Today, there is no such possibility even for users with disabilities.
Source: https://tehnichka.pro/recovery-activation-in-windo...
Accordingly, your activation code did not work during the update.
You can try to re-enter the activation code that was on the seven (suddenly it was recorded somewhere, or try to "find" this key through the ProduKey program).
Another option is to use the Insider Preview, it should help restore the activation of Windows (there is a link, it takes a long time to paint here).
Well, or as already advised - reinstall on the immediately activated Windows.