Once installed, the program set to run every 30 minutes (that you can change) via the windows task scheduler. That means, the program doesn't run always in the back ground, once it does its job, it closes and doesn't run again until the task scheduler runs it.
The new version of CleanMem has included a mini monitor that allows a user to keep an eye on current memory usage and clean the system memory with one click of a button.
CleanMem is a freeware and compatible with Windows 7, Vista and XP. It can be downloaded from this link.