Let me try to offer a non-technical recommendation for installing a memory cleaner utility to your daily arsenal in general, and this application, in particular.
I have read some of comments contributed here and elsewhere arguing that, as a class of software, memory cleaners are either useless under Mac OS X (because the Mac OS supposedly has a built-in memory recoup feature that make such memory cleaners redundant); or that paid-for memory cleaners are nothing but scams to take advantage of ignorance among Mac users, who are unaware that there is a Terminal command which can apparently accomplish the job.
While I do not wish to undermine, challenge, or argue with the insights and conclusions made by experts with more advanced technical knowledge in this area that I currently have or desire to acquire, I do want to offer my own insights and suggestions, which are based, not on theory, but on using a few of these memory cleaner utilities over the past three months or so.
In short, they work. They succeed. They help. You just have to chose the one you like.
My preference is this one where I write: Memory Cleaner X. Not only is it free, which obliterates any critique that it is an attempt to extort money from unsuspecting Mac users, but it is instantly available to you—through its installation as a Menu Bar item which displays the current amount of memory available to you at any given time as a GB number in your Menu Bar. Of course, I suppose that you can probably always interrupt your current workflow and impede your productivity by opening Terminal, inquiring how much RAM is available, and then run a command (is it "Purge"?) to reclaim memory, but really, why bother go through all that DOS/UNIX stuff when you can just click on a button via the Memory Cleaner X menu item and have the utility do all that stuff for. After all, wasn't the invention of a user-friendly GUI (graphic user interface) the genius idea that put the original Mac in a class all by itself and the primary reason for its success? (Watch the movie, "Pirates of Silicon Valley" to see an excellent historical portrait of the computer industry in this regard.)
And, as far as to whether such a utility as a memory cleaner is necessary and useful, I would have to argue—in contrast to those experts who claim that such software is redundant—that, yes, memory cleaners are indeed useful. Find out for yourself.
I was impelled right now to share this tip, because I wanted to perform the simple task of save a web page to a PDF file (I like to save useful New York Times articles), and I encountered the colored spinning wheel. Normally, a command to File > Export as PDF occurs instantly, with no delay, but this time, the colored spinning wheel was telling me that I could not enter any further commands until the Mac sorted out what had to be done.
I quickly glanced to the amount of memory available, as displayed by Memory Cleaner X, and it reported I had less than 200 MB of usable memory, down from a full complement of 8 GB. Aha! There was the problem: the Mac OS, under Yosemite, which my observations taught me is better than Mavericks in this area, has not—contrary to the experts' opinion—refreshed my available memory cache (or whatever element is being used) sufficiently or efficiently enough to provide me enough memory for a simple save to PDF to occur.
When the Mac OS completed its task of exporting that web page, Memory Cleaner X reported that only about 30 MB was left. Obviously, it was time to click on its menu bar item, click on the Cleanup button inside, and force the Mac OS to give me more memory to play with. After I did so, I was rewarded with 3 GB of available memory.
You figure it out! As for me, I already have. So, I have integrated Memory Cleaner X into my daily routine, and I call upon it to clean up memory several times a day. After three months or so of use, I have not encountered any problems at all.