Windows 7 - Windows activation problem

hi guys, i purchased a laptop a few months ago and then upgraded from windows 7 home basic to windows 7 home premium via anytime upgrade......everything was fine and activation went normal...
and today upgraded through windows anytime upgrade as well to windows 7 home professional, but now when i try to activate it says that my product key is not valid!

any advise please guys.

Where do you get your product key?

i bought the laptop with the windows 7 home product key!

If you purchased an anytime upgrade from Starter to Premium, and then another key for Professional, technically that should work as those are supported upgrade paths. What is the actual error message you are seeing?

it says this product key does not work with version of windows..purchase another product key.

i found an app on the net that takes away the activation called WAT ,,,,,,,,,,installed and it works fine but dont know how long that will last......anyway i can go back to premium and use my original product key?

can go back to premium and use my original product key?

Remove that Windows WAT thing you added. Since your purchased Win 7 pro upgrade key doesn't seem to work? contact Microsoft, they will make sure that it starts to works or issue you with a new key that will work.