In an operating system like Windows, we can put the OS in hibernation so all the content in RAM is store in hard drive and be resume later. However, for application software it seems there is no such capability. If the computer is going to run out of RAM soon, I'll need to close some software to make way for the others. Otherwise the computer will become much slower when it use virtual RAM. If that software cannot save the existing configuration before exiting, I'll have to reopen all the files and windows after relaunching.
Although I don't know if this is technically feasible at all (since a software can involve a lot of process and file access lock), I would ask if there is software that can put other application software on 'hibernate' (i.e. to free up the RAM for other software) and let me decide when to resume it afterward.