Shower plants live as long as any other plant. The species of plant affects how long the plant lives, not whether it is in the bathroom or not. Choose the right plants, and you can have a green companion for years to come.
If you want to know the average life span of a plant, the answer is two to five years. However, if not taken care of, house plants won't live a month. If taken great care of, the greenery can live a decade.