The way this works is that on computers running OSX Lion and OSX Mountain Lion, the system (or Finder as MAC calls it) decides when an application needs to run and will automatically terminate it on the fly and reclaim its resources.
I can see automatically terminating applications on a SmartPhone, or other device with meager resources. But automatic terminating applications on a desktop class machine seems to be an unnecessary nuisance! MACS have for greater resources, ram, storage, and processing power. Why Why Why! In fact, OSX not only terminates the application without warning, but the application also disappears from both the dock (unless you opted to keep it there permanently) and from the application switcher, which forces you to re-launch the application.
Write back and tell me what you think!