In app purchase. Playback stopped

[simcario]

Hello, i have The problem described in attached screenshot on the link below 


https://www.dropbox.com/s/vwl66bkc696dn7...3.png?dl=0


 What i have To purchase and how To? 

Tanks in advance

[dwrae]

From the 'Available devices' screen at start-up, you can see a shopping cart under the USB MIDI part. You can purchase from there. The app will also ask you for an in-app purchase (if you haven't done so) when saving a project with MIDI.