The original LifeStraw can filter up to 264 gallons (1000 litres) of water before you discard them. The LifeStraw Go and Steel can filter up to the same amount, but each have a replacement part.
The LifeStraw Go would need be replaced after filtering up to 264 gallons with the LifeStraw Go Replacement Filter. As for the LifeStraw Steel, there is a LifeStraw Carbon Capsule Replacement. The component can filter up to 26 gallons (100 litres) of water as replacement is needed afterwards.