Session Variables in classes

Is it possible to have a class member variable made into a session variable? The only way I have been able to implement this so far is to use a global variable instead of the class member variable. While this is sufficient for my solution where there is only ever one instance of the class on any page, I would not know how to do this if I had multiple instances of the class as they would all be referring to the same var. TIA Richard Lawley