On an old Dell or HP, they choose OEM . Because the license is tied to the motherboard, the system recognizes it and activates itself as soon as it hits the desktop.
Unofficial OEM ESD releases often include pre-installed activation exploits (such as KMS emulators or SLMGR scripts). These tools alter the system's licensing backend. Windows 10 X64 21H1 Pro 3in1 OEM ESD pt-BR JUNH...
