Você pode usar o KMS em um servidor Server 2008 (não-R2) para licenciar versões de nível superior, basta atualizar o servidor KMS. (E também atualize seu sistema operacional do SP1 para o SP2.)
Aqui está a atualização:
This update extends the Key Management Service (KMS) for Windows Vista, for Windows Server 2008, for Windows 7, and for Windows Server 2008 R2 to enable the enterprise licensing of Windows 8 and of Windows Server 2012.
KMS provides support for the following KMS client activations:
•Windows Server 2008 R2
•Windows Server 2008
•Windows 8
•Windows Server 2012
•Windows 7
•Windows Vista
Você pode ativar servidores e clientes usando o mesmo KMS se estiver em execução em um servidor , mas você precisa de um número mínimo de cada antes que o KMS comece a funcionar ... 5 servidores e 25 clientes.
The KMS service does not require a dedicated server. The KMS service can be co-hosted with other services, such as Active Directory® Domain Services (AD DS) domain controllers and read-only domain controllers (RODCs). KMS hosts can also run on physical computers or virtual machines that are running any supported Windows operating system, including Windows Server 2003. Although a KMS host that is running Windows Server 2008 R2 can activate any Windows operating system that supports Volume Activation, a KMS host that is running Windows 7 can activate only computers running Windows 7 and Windows Vista. A single KMS host can support unlimited numbers of KMS clients; however, Microsoft recommends deploying a minimum of two KMS hosts for failover. Most organizations can use as few as two KMS hosts for their entire infrastructure.
Do seguinte artigo da TechNet: link