Memory requirements

I use an IBM Think Pad for work, which is a small, compact and easy to use laptop. So far, there is plenty of space for all my data but if I ever need to supplement it, I can get the exact kind of IBM memory if I were ever to run short. A lot of work I do doesn't need to remain in my computer memory for ever and once a project is complete and approved, I can completely erase all of it from the memory. So, the memory required keeps fluctuating up and down but so far hasn't gotten even close of running short.