Like all art supplies, acrylic paints will keep best if they are stored correctly. They will deteriorate more quickly than oil-based paints but can last for years with a little care.
Firstly, do not store them at too high or too low a temperature. A comfortable room temperature is ideal. Acrylic paints can freeze if they get too cold or dry out if they are too hot. Either way, this can result in the component parts of the paints separating, which will make them unusable.