This is an example of Windows 7 purchased OEM license stickers.
An OEM (Original Equipment Manufacturer) is a company that makes its own products, using components from other companies.
There are many contradictory definitions for OEMs, and different companies may call each other an OEM, depending on their position in the supply chain.
In the Microsoft ecosystem, an OEM would be a PC manufacturer (such as Dell, Acer, Samsung, Toshiba) that uses Microsoft software (such as Windows and Office) in its PCs. The technical term for this type of OEM is a Value-Added Reseller (VAR).