High Availability Add-On Question

Hello --

We have Red Hat Enterprise 7.4 running on one of our systems, and we are going through the process of deploying a twin system at our redundant facility. To that end we are planning on using the High Availability Add-On to create a cluster of the two system , and utilize Pacemaker.

The question that I have is the following: Is the High Availability Add-On a separate product that needs to be purchased, or is it already included with our subscription?

Thanks.