[bargl]

The same is true of Visual Studio you can apply a license in VS. I just did it in VS 2015. No sign in required.

[ultramancool]

I've got MSDN, can I do this? Necessitating the signin really pissed me off.

[bargl]

If you have a license key then yes.

https://msdn.microsoft.com/en-us/library/gg442061.aspx