How do I go from NIS to NS?

I'm running NIS on 3 machines. I understand that NIS has been rebranded and is now called NS.

Is NS literally the same as NIS such that the keys are interchangeable? (It seems that NS allows 5 seats rather than 3 for NIS. Maybe there are other differences.)

Should I be replacing NIS with NS. If so, how do I do that?