That was no specified period.
Never over-charge and discharge; storage it in a LiPo guard bag, temp is around 13 temperature, dry and cool place in 40% capacity; keep from acuity items, water, fire, etc. When you storage a long time, charge it to 40% per 2-3 months. Then it can be used around 2-3 years.

Of course, some accident maybe let it have a very short lifespan.

The lifespan depend on your using habit.