vCenter Server provides licensing infrastructure that you can use for management and reporting of licenses that apply to ESXi hosts, vCenter Server, and certain solutions such as vCenter Site Recovery Manager, vCenter CapacityIQ, vCenter Operations Manager, and so on.
Licensing in vCenter Server is implemented using license keys. You can assign one license key to multiple licensable objects of the same type if the key has enough capacity. Suite license key can be assigned to all suite components. You cannot assign multiple license keys to a single licensable object. For example, you can assign one license key to multiple vCenter Server systems in a Linked Mode group, but you cannot assign multiple license keys to a single vCenter Server system.
ESXi hosts, vCenter Server, and solutions have different licensing models.
ESXi 5.x hosts are licensed with vSphere license keys that have per-processor capacity. You can assign a vSphere license key to multiple ESXi hosts if the key has large enough processor capacity to cover all physical processors in the hosts. When you assign a vSphere 5.x license key to an ESXi host, the amount of processor capacity of the key that is consumed is equal to the number of physical processors in the host. For details about how to apply the licensing model for ESXi hosts, see Licensing for ESXi Hosts.
vCenter Server systems are licensed with vCenter Server license keys that have per-instance capacity type. A license key for vCenter Server determines the number of vCenter Server instances that you can license with the key.
Solutions are licensed depending on the specific usage and licensing needs of each solution. For example, vCenter Site Recovery Manager and vCenter Operations Manager are licensed on a per-virtual-machine basis.
The licensing infrastructure in vCenter Server provides functions that you can use to implement and monitor the licensing models of ESXi hosts, vCenter Server, and solutions.