Possible Duplicate:
One License and multiple PCs, how does it work?
I know for previous versions of Windows, you were allowed to install the same key onto 3 different computers. Is this the same with Windows 7?
Windows – How many computers can use a single Windows 7 license key?
license keywindows 7
Best Answer
Windows OEM - One machine and dies with that machine. Windows Upgrade - Upgrades a single copy of Windows to the latest version. Windows Fully packaged Product - Only one machine, but can be moved to another machine (can only be installed at one place at any one time). Windows 7 Family Pack - 3 licences for different computers at any one time.
Windows Activation is designed to stop pirates from installing on hundreds of computers, if you just install it on a couple of machines, it will work - and if you hit the limit, then ring them up, they usually authorise it HOWEVER it doesn't mean it is legal to break the limits just because it works.