We started using software licensing on the 12G servers and newer. The 11G servers, like the R710, would still use hardware for licensing. The only thing you should need to use the enterprise port, is the daughterboard it is connected to.
You might try checking in the Dell Digital Locker.
The license should show up, if you log in with whatever email address that would have been tied to the order.
No one within our team knows the e-mail used for the dell digital locker (people leaving etc). Is it possible that you can see what e-mail address was used from the service tag ?
At the moment 2 of our servers are not remote via drac as we need the license due to the motherboard swap outs.