he has been using it for a year and suddenly it did this? did he try to reinstall windows or anything like that? what had he done prior to that popping up? Has he been doing all the windows updates on it and which version of windows is it running?
Is this a second hand pc or brand new where was it purchased?

Right click the desktop icon 'computer' ... select properties.

At bottom of that page .. change the product key... enter the key on his install dvd or written on the side or bottom of his computer... or maybe shows right there on bottom of page.

If it fails then,,, follow the steps if offers to get genuine. At worst a long on hold phone call to microscroft

I once had a problem like this, but it occurred when I was installing a brand new, legal version of Microsoft Office, and it happened right after the install. A call to Microsoft straightened it out.

One other thought is that this might be a virus, so he should not be clicking on any windows, or paying for anything, or installing anything.

My recommendations:
1. Run a full anti-virus scan, plus a Malwarebytes scan
2. Call Microsoft

I just talked to my son.. He said he rebooted & that message went away.. I hope it stays gone. I doubt Microsoft helps U free. Maybe we won't need their help..
Thanks for the replies.
Dar

Actually Microsoft's verification program is free.