Computers, which are built by large manufactures that come with Windows
Pre-Installed, come with two (2) Product Keys:
A) OEM SLP: This key comes pre-installed in Windows, when it comes from the Factory. This key is
geared to work with the OEM Bios Flag found only on that Manufacturer's computer
hardware. So when Windows was installed using the OEM SLP key (at the factory)
Windows looks at the motherboard and sees the proper OEM Bios Flag (for that
Manufacturer and that version of Windows) and Self-Activates.
B) COA
SLP: This is the Product key that you see on the sticker on the side (or bottom)
of your computer. It is a valid product key, but should only be used in limited
situations (such as if the OEM SLP key stops self-activating for whatever
reason). (Note: All manufacturers that use the OEM SLP system are required by
contract to include a Certificate of Authenticity (COA) sticker, that has a COA
SLP key, on the computer)
The Key is defined by the License - for Pre-installed Windows, the Licenses are OEM (as above). For Retail or Upgrade Licenses, the Key is in the packaging.
It does not change.