If your copy of Windows is not genuine, you will get an error message and Windows will no longer work.
There is an easy fix you can apply in minutes that can get rid of this error message until you purchase a legit copy or solve your product key issue in Windows.
Follow these steps to fix
If you do this too many times, you will get:
error 0xc004d307 The maximum allowed number of rearms has been exceeded
You will need to edit the registry to get around this with the fix below but I would only advise this for advanced users and make sure you backup your registry first!