I used Memory Clean 1 and 2 previously and considered rather long and hard before purchasing Memory Clean 3. I thought Memory Clean 2 was about as useful as a memory management tool could be. Nevertheless, I obtained Memory Clean 3. I am not sure that it does anything more in freeing up memory than its predecessors, but wow does it help me with application management. I usually have multiple apps open, switching back and forth between them. I often forget to close an app when I finish with it thinking that I may still use it. Memory Clean 3 reminds me that it is still open and unused (I can set the time interval). I close the app, and Memory Clean 3 returns the memory to the operating system. You say Mac OS X does that anyway. Yes, it does. But Memory Clean 3 returns much more memory than just the memory allocated to the app. While I don't know the internals of Memory Clean 3, it appears to not only return the memory allocated to the app, but also memory allocation for buffers, caches, etc. (I use Extreme Clean). Having performed these tasks, it then tells me how much memory it freed up. For comparison purposes I can check Activity Monitor versus what Memory Clean 3 says it returned to the system. (I assume Memory Clean 3 is truthful.). Two major points here. First, memory freeing is dynamic and automatic as is Mac OS X but to a greater extent. Second, I maintain a larger amount of unallocated memory at all times because I am dynamically and automatically running Extreme Clean with the closing of each app. I don't have to do anything except close the app if I'm finished with it - which I would do anyway. Incidentally, if I have multiple apps that I want to leave open all day, I am able to add them to an exception list in Memory Clean 3 thereby eliminating spurious notifications.
So back to my opening sentence. Memory Clean 3 appears to be the same as Memory Clean 2 in terms of managing memory. However, the dynamic and automatic aspects as well as the reminder elements make Memory Clean 3 much superior to Memory Clean 2. If you don't have a memory management tool, please seriously consider Memory Clean 3. I believe you'll be very pleased with your purchase.