what version of windows, if youre on windows 10 home it doesn't have the group policy manager

have you tried this;

win key + X
click cmd prompt (admin)
alternatively just search cmd right click it and run as admin
in the cmd window type slmgr -rearm
reboot then go to the settings page where your windows key is and see if it still has a warning

Ah yeah Win 10 Home. Cheers.

What does that do?

it's supposed to extend the windows activation, probably not a permanent solution but it should at least stop the pop while you figure out the issue.

How did you get the computer? If it's a laptop or you bought a PC somewhere, from what i'm reading it sounds like they might have used a KMS to install windows as opposed to a key without an expiry date. If you built the PC yourself I would just try to force the activation again.

I suggest reading this and using the commands to check when it will next expire, and how to force a reactivation using the key you have.

https://www.howtogeek.com/245445/how-to-use-slmgr-to-change-remove-or-extend-your-windows-license/

I did that and now it says my Windows is not activated :D

I built the PC. But then my hard drive got corrupted and a forum poster helped me put Windows onto a USB and install it that way.

There is a key (shows only last five digits) when I go on Windows activation settings. Im not sure if I have the full key at home somewhere though.

There's tools to view the key, google belarc advisor. You run it and it will tell you the keys that are present.

However it's starting to sound like you reinstalled but just didn't put the key back in? In which case just find your key at home, then use the slmgr command in the link to apply the valid key.

I went crying to Microsoft and they helped me fix it.

Thanks man.

when i was ten i uninstalled windows on accident when trying to dualboot ubuntu and i cried about it to my laptop manufacturer and they gave me an unlimited copy of windows