The lifespan of a portable power station depends on its quality. A higher-quality unit will last longer, but even lower-quality units can be used for years if you take care of them properly.
The most crucial factor in determining the lifespan of a portable power station is the amount of time you use it. If you use your device heavily, it could shorten the life of the battery.
In general, however, most portable power stations will last between 3 and 5 years before needing to be replaced or repaired?