No, you can use it as a generic MIDI controller, of course.
No, offline authorisation is not possible. It used to be possible with Service Center, the precedesor of Native Access.
Maybe in future, NI considers to add offline, but if and when... Nobody knows....
@ZMaslanik I think that you may use S keyboard on offline computer. I guess you may download the drivers from NI pages and also Komplete Kontrol. At least older version, which is anyway better. And those do not need authorisation AFAIK.
So, I guess you could even use NKS features of NI Keyboard for plugins that do not need online authorisation.
Otherwise, in any case you could use NI keyboard as generic MIDI keyboard.....