Hello
The licesnse you purshase depends on what you will use it.
Defenitly you need the AP licesnse
The PENGF license you need it if you using the Firewall on your controller(with the IAP it comes build in and you dont need any licesnse for it but with controllers you do!)
There are other licenses in which you wiill be able to read here:
http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/New_Licenses.php
The other important thing is that i see that you planning on buying a used controller.
On the perspective of a partner which i am i work for a Aruba partner, you will need to change the end user name of that controller.
You also need to check about the support(controller does not have lifetime warranty) so you willl need or at least i recommend you to purshase the support for it(it will cost you more money depending when did the current owner stop purshasing the support. Remenber for this you will need to change the ownership of the controller to you!
Does that used controller comes with some licesnses ? or come with none?
remenber purshase the arubacare for that Controller, and ask them to put it to your name, that the first thing you need to do. You dont want to be an unlucky one that in like 4 months of use it dies and then you will need to buy a new one :)
Cheers
Carlos