Your salt cell will not last forever. In fact if you get over five (5) years out of it you are in good shape. There really is no cost savings in a salt cell pool over a chlorine pool, since the new cell will cost you over $500.00. But, the salt water does feel more natural because it is, and when they are working, the pool rarely gets algae or cloudy water because the Salt System is producing chlorine continually, which makes it very easy to maintain.
Most of the cells like the ecomatic salt cell will let you know when they are dead or dying. Most have a red LED light that let you know that your cell is dead or dying. A good indicator is that after cleaning the cell and adding salt the cell isn’t generating chlorine at all. The 5 year mark is also a good indicator.