There is no need to check originality of windows 7 , Because if the version is pirated then it will automatically notified you after some days. But if you really want to know about your windows version then you can follow these
The first way to validate that Windows 7 is genuine is to click on Start, then type in activate windows in the search box.
If your copy of Windows 7 is activated and genuine, you will get a message that says “Activation was successful” and you will see the Microsoft Genuine software logo on the right hand side.