There is no more /console RDP switch since Windows Vista.
Yes, the Remote Desktop Services mmc snapins that you were used to in 2008 have been removed.
A Windows license grants you two "administrative" simultaneous remote desktop sessions before you need to install the Remote Desktop Services role with CALs. There is no "2 administrative connections +1 console (which would make 3 simultaneous interactive sessions)" though. It's just two. You can use the /admin switch with the Remote Desktop Client to avoid using up CALs when the RDS Session Host role is installed, but you can only have two admin connections at a time regardless.
From this Microsoft article which does a great job of explaining:
At any point in time, there can be two active remote administration sessions. To start a remote administration session, you must be a member of the Administrators group on the server to which you are connecting.
To RDP to a Windows Server 2012 VM hosted on Azure, you need to ensure that you have opened the endpoint in the Azure portal (think of it like a firewall ACL) in Azure, and also make sure RDP (port 3389-in) is allowed through the Windows Firewall as well. Then you need to make sure you're logging in with a user account who has 'Remote Desktop Users' privileges or better.
Next, disable the setting Restrict Remote Desktop Services users to a single Remote Desktop Services session by using the Group Policy Object Editor MMC-snapin to edit your Local Policy.
It's under Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Connections.
Run gpupdate after you make changes to the policy to apply them immediately.
I have a Server 2012 VM hosted on Azure, and I just followed the above steps, and now I am logged in twice, interactively, as the same user.
I found the answer. Looking at the Network and Sharing Center, the RAS (Dial in) Interface was set to Public network. I had turned the firewall off but only for private networks. Turning it off completely solved the problem.
Best Answer
So we're left with "Fair Share" resource sharing, enabled by default for Remote Desktop Services in 2012+, for CPU, Network, and Disk I/O. But not memory. So no, no memory balancing like we had with WSRM. Why did they specifically leave memory out of the FairShare policies? I don't know.
You can implement fair sharing of memory across virtual machines on a Hyper-V hypervisor, but that is not the same thing as a Remote Desktop Session Host. So as of this moment I would say that they've taken that very particular functionality away and left us with no alternatives. I suspect (this is conjecture) that is what Microsoft meant when they stated "Similar functionality is provided by Hyper-V." That it was sort of a naïve idea that "well, since the whole world is moving to VDI anyway, just use Hyper-V to balance memory across VMs." But again, I am ready and willing to be proven wrong.