VMware vCenter Heartbeat Licensing

VMware Heartbeat Licensing?  It's a tricky question and one I have the answer to.  1 single license (yes that's just ONE) will entitle you to run Heartbeat on a vCenter Server AND a separate MS SQL server.  The caveat being that you are only supposed to protect VMware related databases (this could mean running VMware databases on a separate instance).  The other fact to note that if you have this type of setup, you will have 4 instances of the Heartbeat software running, 1 on the primary vCenter server, 1 on the secondary vCenter server, 1 on the primary Database server and 1 on the secondary Database server.