So what happens? Nothing. Windows 10 Home or Pro is installed, and you can use it. There are just two limitations that I have come across:
Watermark on the lower right-hand corner saying Activate Windows You cannot use anything under Personalization e.g. change wallpaper, accent colors, lock screen, themes, etc. All options are there, they are just grayed out and inaccessible
Other than this you have a fully-functional Windows 10 OS. There are no nag prompts either and yes, you get all system updates (at least for the year).
ref:
https://www.windowscentral.com/you-do-not-need-activate-windows-10
You get a watermark in the bottom right hand corner of the screen and you can't utilise Microsoft account services such as syncing settings...