I really don't think there's a limit to how long plants can live, as long as you keep them watered and free of disease. I don't usually keep my plants for very long, since the only thing they are good for after they have produced their batch of seeds is for pollinating other plants (which I can do with new plants). Since there are only 15 pots, I usually make the seeds I want, sell the current batch of plants, and plant all new seeds.
