Do I have to use the nanoKontrol2?

No, you don't have to own Korg's nanoKontrol2 in order to use Sunday Keys. 

However, the nanoKontrol 2 controller does come pre-assigned to our Sunday Keys for MainStage or Ableton templates and is a great way to interact with it live. It will give you 8 faders, 8 knobs and 35 buttons for sound shaping control that send reliable midi and are ready to go without any additional mapping work - it truly is plug and play!

Check out the video below for more: