Windows 10: Asking to activate windows after already activated

I originally bought a pc with windows 8.1 installed and the product key sticker on the side. I later upgraded to windows 10 for free. I upgraded this pc with a new motherboard some months ago. This week it asked me to active windows again, so I typed in the windows 8.1 key from the sticker. It activated and everything was fine. Today it asks me to activate again, however, this time the key will not work. Is there any way to get this key to work? Thanks

:)

 

Windows Activation?

Windows will do this if it detects a significant (their word, questionable use) hardware change, and will ask you to reactivate.

After a key has been activated X number of times, you will have to call to activate it.

Couple of tips for the phone call: You can use your keypad, and when they're telling you keys, instead of saying "Repeat that" and "Continue" type 1 and 2. With these tips, that activation call will only last you about 4 and a half minutes.

 

Windows activation . . .

In the Windows activation status page is it still showing as activated, or do you have something like 3 days to do it in?

 

Windows Vista Activation

I have 4 sytems in my home running vista(1 ult.-3 prem).The ultimate & 1 premium took SP1
wthout a hitch.1 premium required re-activation?,The other premium did not list SP1 in windows up-date,So i manually installed it without any re-activation required.
Also have to add that SP1 has increased performance in every comp.The ultimate machine actually got a 1,100 point increase in 3d 06 without any other changes at all.