Pooled capacity in Citrix ADC is a licensing framework that comprises a common bandwidth and instance pool that is hosted on and served by Citrix Application Delivery Management (ADM). From this common pool, each ADC instance in your data center, regardless of platform or form factor, checks out one instance license and only as much bandwidth as it needs. The license file and, so the bandwidth are not bound to the instance. When the instance no longer requires these resources, it checks them back in to the common pool, making the resources available to other instances that need them.
In ADM service, one of the agents is the license server. In on-premises ADM, the on-premises server is the license server (even if agents are deployed).
This licensing framework maximizes bandwidth utilization by ensuring that instances are not allocated bandwidth more than their requirement. The ability of the ADC instances to check licenses and bandwidth in and out of a common pool also enables you to automate instance provisioning.
You can increase or decrease the bandwidth allocated to an instance at run time without impacting traffic. You can also transfer the licenses in the pool from one instance to another.