Official KMS is a method used by enterprises to activate many computers on a local network without each device needing to connect to Microsoft.

is the standard, stable release version of Windows 8.1. It introduced several improvements over the original Windows 8, such as the return of the Start button and better multitasking features. When Windows 8.1 is unactivated, it often displays a "Build 9600" watermark on the desktop and restricts personalization settings like changing your wallpaper. Understanding KMS Activation

Активация клиента KMS и ключи продуктов - Microsoft Learn