This adds a extra layer of security as not only do they need to know the key name used in your domain they will also need to know your domain license token.
This security is used to protect the endpoints from penetration attacks.
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2