Ad-Aware Plus and Ad-Aware Pro trials can be downloaded from Softpedia. The price difference between these two versions is well over $10, as Pro sells for $39.95, while Plus comes with a $26.95 price tag.
As for the features compensating for the price difference, the top priced issue comes with the advantage of the network real-time protection in Ad-Watch Live!, network drive scanning Do Not Disturb Mode (suspends interruptions when an application is detected as running in full screen mode), Lavasoft Toolbox and command line support. So all these make for the 13 bucks difference.
As for the free version of Ad-Aware, as expected, it is the least feature rich of the three. The downhill in this case is represented by the lack of antivirus protection. Ad-Watch Live! will only care for the processes running on the system, and there is no scheduling function, Toolbox or technical support from the developer. Sure, the features missing in the Plus edition add to these as well, but you will get Genotype Detection Technology for uncovering spyware traces (a proprietary malware detection system based on heuristics), Download Guard (scans your downloads for threats) or Neutralizer (advanced malware removal tool); all these are fresh introductions in the latest Ad-Aware, available in all editions.
In order to provide ease of use for both the advanced and the beginner user, Lavasoft introduces with this version of Ad-Aware a split interface that features a Simple and an Advanced mode. As it makes sense, the Simple mode is a reduced adaptation of the full-fledged program that shows only modules that are absolutely essential to the user.
The license for each of the two versions can be acquired for either one, two or three years, with a discount depending of the period you buy it for. Thus, a Pro license for three years costs $67.92, and the price for the Plus edition for the same period of time reaches $45.82.