If your vSphere 6.0 environment consists of vCenter Server 6.0 and 5.5 systems, you should consider the differences in the license management and reporting between vSphere 6.0 and vSphere 5.5.
The License Service in vSphere 6.0 manages the licensing data for all ESXi hosts, Virtual SAN clusters, and solutions that are associated with the vCenter Server 6.0 systems in the vSphere environment. However, every standalone vCenter Server 5.5 system manages the licensing data only for the hosts, solutions, and Virtual SAN clusters that are associated with that system . Licensing data for linked vCenter Server 5.5 systems is replicated only for the vCenter Server 5.5 systems in the group.
Due to the architectural changes in vSphere 6.0, you can either manage the licensing data for all assets that are associated with all vCenter Server 6.0 systems in vSphere, or manage the licensing data for individual vCenter Server 5.5 systems or a group of linked vCenter Server 5.5 systems. The licensing interface in the vSphere Web Client 6.0 lets you select between all vCenter Server 6.0 systems and vCenter Server 5.5 systems.