Each vSphere kit or edition is licensed on a per-processor basis, according to the number of physical processors (CPUs) on each host. In the case of vSphere kits, the listed entitlement for CPU capacity discussed later in this document applies to more than just one host. Customers can purchase and deploy or redeploy any mix of servers, as required; each processor in a socket may contain multiple cores. Customers may deploy vSphere on physical processors that contain up to six processing cores at no additional charge (see following note). Customers that require limits beyond the processor entitlements must purchase additional vSphere licenses.
Note: VMware vSphere Advanced and Enterprise Plus editions include expanded core entitlements up to 12 cores per CPU. (Source