I finally got in touch with one of my vendors who was able to explain the licensing to me. The answer is:
For 90% of most deployments, 2 licenses are typically used:
1) JW472AAE - Aruba Controller Per AP Capacity License
This is a perpetual license that allows one access point to be managed by the controller. You need one of these for every access point you want to connect to and manage with the controller. Your basic license.
2) JW473AAE - Aruba Controller Per AP PEF License
This is a license that must be acquired on top of the JW472AAE license. This license isn't mandatory, but it allows more advanced role-based access controls on a per AP basis. (Like if you wanted to have a restricted network and an open network, but you had one or two devices that normally connect to the open network but need access to resources only available on the restricted network.)
It's important to note that the PEF license augments the capacity license - it does not replace it. (Think: more $$ to use more features.)
My vendor said that for 90% of most deployments they see, the above two license types are really the only two to be concerned with. There are others that offer increasing functionality and features at an exponential price increase.
Also, Aruba does offer non-perpetual licenses that must be renewed every year. So, be very careful and talk to your vendor before you actually buy any licenses. In most scenarios, you'll probably want the perpetual licenses. There are; however, cases where an annual license may be a better fit for you.
In closing: I noticed that there seem to be large-quantity license "packs" available at significantly better prices than buying the licenses individually. For certain enterprise deployments, these options may be more viable.
My Opinion: It honestly confuses me why Aruba has made this process so complicated. They have two series of AP: IAP and AP. IAP can work with or without a controller whereas AP are marketed specifically for use with a controller. Why they charge $1500+ for an AP and then force you to pay more just to be able to use it seems a little "greedy" to me. I'd say that if you're going to market a product to work with another product, the licensing should be included in the price - especially at that price point.
Don't get me wrong ... Aruba's got some really nice high-quality stuff ... but you can tell they like some of their stuff just a little too much.