Your Original Equipment Manufacturer (OEM) Product Key
Genuine Microsoft Label and Microsoft Digital Marker
Newer systems come with a Genuine Microsoft Label (GML) like the following:
These labels just indicate the presence of a Windows License. The 25 digit System Locked Preinstallation (SLP) Product Key resides with a Microsoft Digital Marker (MSDM) Advanced Configuration and Power Interface (ACPI) table embedded in the Unified Extensive Firmware Interface (UEFI) BIOS.
The correct installation media discussed below will automatically input this SLP key during installation and you should’t need to manually look it up to input it. The UEFI BIOS ACPI Table MSDM tab can be checked with RWEverything.
Code of Authenticity (COA)
In the past systems shipped with Windows 7 OEM will have a code of Authenticity (COA). This is a paper label which contains your Edition of Windows alongside your 25 digit OEM Product Key. This Product Key can be used with Windows 10 Installation Media but is not typically used for Windows 7 installation (see System Licensed Internal Code):
Since the launch of Windows Vista the COAs provided by Microsoft have been of low print quality. In order to reduce their likelihood of fading OEMs typically placed them under the battery compartment in laptops. Use your phone to take a picture of the COA before Windows 10 installation:
System Licensed Internal Code (SLIC)
For Windows 7 OEM there was also a BIOS based activation mechanism. The System Licensed Internal Code (SLIC) Advanced Configuration and Power Interface (ACPI) table is embedded in the BIOS. The BIOS ACPI Table SLIC tab can once again be checked with RWEverything.
A SLIC version of 2.1 is eligible for Windows 7 OEM System Locked Preinstallation. A SLIC Version of 2.0 is for Windows Vista (End of Life) and a SLIC Version of 1.0 is for Windows XP (End of Life).
OEM branded installation media such as the Dell Windows 7 Reinstallation DVD will install Windows 7 OEM with a generic System Locked Preinstallation (SLP) key. If the SLIC and OEM ID match the SLP key and Windows Edition then offline product activation will occur.