Licenses are a way to prevent people from overfishing populations. Certain populations have been overfished to the point of being endangered, and if a species gets erased out of an ecosystem, the overlying ecosystem gets thrown out of place depending on how key of a species the fish was.
There are some species the gov does not care about eg the invasive lionfish and asian carp
Just a one time purchase. Op probably meant they have bought 0 pokemon games but bought this