vmb01 ... at this point, you should talk to your sales team to validate EXACTLY what is required. If you deploy vCenter 5.1 + vCloud Suite .... you'll probably be fine. If you buy vCloud Director separately, it's just a license pack for it (afaik).
So there were a lot of changes as things went along.
vCloud 1.0 paired with vCenter 4.1 release time frame. So there were two singular keys for vCloud and vShield respectively. I use the term vShield 'free' loosely, as I think it was technically called 'vShield Basic License'. Also, vCloud didn't support things like VPN and load balancer ... so this was not included in this basic/free license.
vCloud 1.5 paired with the vCenter 5.0 release, and kept the same license setup as the prior version.
Then comes along vCloud 5.1 with vSphere 5.1 ... where the new license structure was introduced, where one key could unlock many products. This is very handy, as the 'vCloud Suite' key will unlock vCloud, vShield, ESXi, etc, etc ... assuming you are using vCenter 5.1 (which has a dedicated key vs the one for many products).