What is activation key for windows 7 pro?

if it is a legitimate licensed windows 7 contact Microsoft help line.
https://support.microsoft.com/en-us/contactus?forceorigin=esmc
if it is an upgrade it needs to detect older version of windows on computer if it was installed on another p.c or different hardware setup it has to be removed from the old hardware setting and given a new key even if same computer.

http://windows.microsoft.com/en-us/windows/activating-windows-faq#1TC=windows-7

Buy it or crack it, but dont ask for licence keys...

Simple. Buy one.

You may need to download skype and ring up Microsoft and do the online Activation, I had to it for my Windows 7 x64 upgrade to Windows 8 Pro x64.
I downloaded Skype, and Rang up Microsoft UK since it was free and I was able to activate my Windows 8 Pro x64.

Have you tried Windows 8 Pro 64 bit?

Hi,
Go to Control Panel \ System click on change product key then enter Valid product key and click next to activate Windows 7. you can also activate your Windows 7 online.

you might be given it if you ask nicely

CyberCafePro 5 was not compatible with Windows 7. CyberCafePro 6 is free and compatible with Windows 7 32bit and 64bit.