Darren McFerran

You need to reactivate through the Bandlab assistant, under the apps tab click the "open" tab next to the Cakewalk logo and choose "Refresh Activation".

You don't even need to do that... Just tell your vst instrument track to listen to all midi inputs and set it to omni, I use two midi keyboards, a novation control surface (zero SL mkII) and a breath controller all at once feeding just one midi track!