No restriction exist for the number of virtual machines that can consume the available capacity in a vRAM pool. No restriction exists on how virtual machines are distributed across all hosts in a vRAM pool either. However, you must maintain the ESXi 5.0 in your environment in compliance with the vSphere 5.0 licensing model.

Two requirements must be satisfied to maintain compliance with the vSphere 5.0 licensing model.

Every physical processor in an ESXi host that runs vSphere 5.0 must be licensed.

The 365-day moving average of daily high watermark of the vRAM usage for a vRAM pool must be equal to or less than the amount of available vRAM capacity in the pool.

The 365-day moving average of daily high watermark for a vRAM pool is calculated by using the maximum usage for the pool for each of the past 365 days to calculate the average value. You can track the 365-day moving average by using the license reporting function in vCenter Server. To view the value of the 365-day moving average for a vRAM pool, you can view the vRAM usage for the corresponding vSphere product edition for a period of one year. Using the license reporting function, you can also set custom thresholds for the license usage of particular products to get notifications when the license usage for the products exceeds certain limits. For details about using the license reporting function in vCenter Server, see Viewing License Use

Because licensing compliance for vSphere 5.0 is based on the 365-day moving average, temporary peeks of vRAM usage might exceed the total capacity that is available in a vRAM pool without making the pool out of compliance. For example, suppose the vRAM usage for vSphere 5.0 Standard on the current date is 210GB, and the available vRAM in the pool for vSphere 5.0 Standard is 200BG. However, the 365-day of moving average for vSphere 5.0 Standard is 195GB and the vRAM pool for vSphere Standard is in compliance.

If you have vSphere 5.0 Essentials or Essential Plus kits, you cannot use more than 192GB of vRAM for powered-on virtual machines. If the memory that is configured to powered-on virtual machines reaches 192GB, you cannot power on any new virtual machines or hot add memory to already powered-on virtual machines.