I've added the Addictive Drums 2 synth to a MIDI track.  I found a kit I want to use - United Pop, Fat Sound - but when I go to the "KIT" view, all the drums display "NO LICENSE" beneath them so I cannot use them in my track.  For example, for "TOM 1", I have "13x9, Leedy and Ludwig (Hi)".  What do I have to do to get the license?  Thanks.

Buy the kit. AD2 shows all the kits available whether you own them or not.

So not all the kits come with the SONAR X3 license?

Correct, that kit was released this year. I am not sure exactly what was bundled with the later versions of X3. My guess is it was the upgrade to AD which would include the three studio kits. IOW, the kits which came with the original AD.

Yeh you have to buy the kits you can sample some...the one that I missed out on was the reel drums...I really want them but I went for Session Percussions Pak Funk Pak and modern Jazz Pak for my drums
 
For the Keys...Electric Grand pak Mark one and studio Grand 
 
I will expand this year though and add some more instruments to the ones I have already which is not much really!