The amount of vRAM that vSphere 5.0 license keys provide is aggregated into vRAM pools for every license edition when the license keys are assigned to ESXi 5.0 hosts.

When you assign a vSphere 5.0 license key to one or more ESXi 5.0 hosts, the key adds its vRAM capacity to a vRAM pool. For example, if you assign a license key of vSphere 5.0 Standard with a capacity of 10 processors and vRAM capacity of 320GB, the key adds 320GB of vRAM to the pool for vSphere Standard.

A vRAM pool aggregates all vRAM entitlements of vSphere 5.0 license keys of one edition that are assigned to ESXi 5.0 hosts. A vRAM pool for one license edition is available for one vCenter Server or a Linked Mode group. The amount of vRAM that is available in a vRAM pool for a license edition determines the total amount of memory that you can provision on powered-on virtual machines running on ESXi 5.0 hosts.

For example, you assign license key A of vSphere 5.0 Standard to an ESXi 5.0 host. The key has a capacity of six processors and entitles 32GB of vRAM. The vRAM pool that is created for vSphere Standard contains 192GB of vRAM that license key A provides. Later, you assign license key B of vSphere Standard to another ESXi 5.0 host. License key B has a capacity for 10 processors and entitles 32GB of vRAM. License key B adds 320GB of vRAM to the vRAM pool for vSphere Standard. The total amount of vRAM that is available in the vRAM pool for vSphere Standard is the sum from the vRAM entitlements of license key A and license key B, which is 512GB. In this example, you can provision up to 512GB of memory on the virtual machines that run on the ESXi 5.0 hosts that are licensed with vSphere 5.0 Standard license keys.