If you are referring to RAM (which I assume you are based on what you wrote). You've misunderstood a number of things. Firstly, RAM memory had nothing whatsoever to do with storage memory. This tablet comes with either 16gb, 32gb (or theoretically 64gb) storage (sometimes referred to as memory). On top of this, you can add an sd card of storage space up to 64gb. That is the memory used to store programs, files, pictures, videos, etc. If you want to store files on your external sd card, you can either do this manually or set programs to store the files there. Some programs will not allow this, depends on who made the app. The second type of memory, is RAM memory. This tablet comes with 3gb. Total. The end. Nothing you accessorise your tablet with will change this fact. The ipad air for comparison comes with 1gb.
Traditionally, in a PC, you wanted lots of free RAM memory, if all the memory got filled up by having too many programs in use at the same time, your PC would lock up. I believe in windows 8, it now works more like Linux and Android, so this isn't necessarily the case. Android fills up the RAM memory with programs in preparation for them being used, not having the RAM filled is not going make your tablet work better or more efficiently... It is simply a waste of RAM, and you may as well be using a tablet with less RAM. As you need memory, it is automatically freed up, there is nothing you need to do, and no program you need doing this for you.
However, one point you made can be rectified. If you never use a program, and you don't want it ever running in the RAM ready for use, you can disable it (except the programs that Samsung has disabled the disable on

). There are 2 ways to do this. Go to settings, general, application manager, swipe over to the "all" column, and disable the programs that you don't use and allow disabling.
Method 2 is for actual programs only, not processes (like the application manager includes), but it allows disablinga couple programs that the application manager does not, such as knox. First, if you are using a different launcher than touchwiz, clear defaults, press home and choose touchwiz. If you don't know what I mean by launcher ignore that part. Go into your app drawer, press the settings button, and choose uninstall/disable apps. The ones with the minus symbol, you can disable or uninstall. If you want to enable them later, you can choose show disabled apps in the same settings menu in the app drawer, and enable them from there.