The Multiple Activation Key, or MAK, and the Key Management Service, KMS, are volume activation services from Microsoft that allow business owners to conveniently automate the activation of multiple computers. MAK is a one-time service involving Microsoft's activation server, while KMS allows for activations to be completed on one's own network, thereby removing the need for each computer to connect to the Microsoft activation server. Both services are available for the Windows 7 operating system.
Two types of MAK service exist, MAK Independent Activation and MAK Proxy Activation. The former mandates that each computer connect to the Microsoft activation server via either Web or telephone. With the latter, a centralized request is made using the Volume Activation Management Tool, or VAMT, enabling administrators to activate hundreds of systems in one quick and clean sweep.
The KMS service requires that a network contain a minimum of 25 Windows 7 computers. Unlike the MAK service, it doesn't require that each computer be connected to Microsoft. Instead, a KMS host key is provided, enabling one of the network's servers, designated the KMS host, to connect to Microsoft. Once it has done this, the KMS host can activate an unlimited number of computers on its network.
MAK allows small businesses with fewer than 25 systems to participate in volume licensing. Furthermore, MAK activation can be performed anywhere, so long as the location has Internet access, meaning you can activate both remote and in-house computers. Another notable advantage to consider is the similarity between the MAK service and traditional Windows activation. The two processes are nearly identical.
The key advantage KMS provides over MAK is that a single key can activate an unlimited number of clients. With MAK service you need to purchase an additional key every time you install a new system or even when you need to reinstall Windows 7 on a system you already own. Another advantage lies in deployment. You must plan new installations beforehand with MAK, whereas with KMS you need not concern yourself with activation before or during deployment.