How to check if Windows 7 license key is valid?

Question

Windows

Hello.
There are several windows 7 license stickers on them with serial numbers. How do I know if they are enabled or not? Without a clean installation of Windows on the computer and entering a serial number.
Maybe somewhere on the site there is such a feature, you enter the serial number from Windows, and he writes to you whether it is activated or not?
Tell me please.

Answer 1

Until the moment of its activation - no way!