The life of a glow stick depends on many factors. The shelf life can be up to four years, while the active life is typically a few hours.
Glow sticks produce light through a chemical reaction. The kinetics, or rate of the reaction, determines the life of the glow stick.
Increasing the temperature speeds up the reaction. The glow stick is brighter but does not last as long. Lowering the temperature slows down the reaction. The glow stick is dimmer but lasts for a longer time.
Once you activate a glow stick and want to store it, place it in the freezer. Warm it up when you are ready to use it. This gives it the longest life.