It is said that Oswald Kernow (the last King of Vale) took the idea for the Huntsfolk (that is to say Huntsmen and Huntresses), and their administrative association, from the four Great Knightly Orders of his home Kingdom. In those days, a Knight would be dispatched to deal with Grimm wherever they appeared within the borders of the Kingdom, paid only in food and board, before returning to their Order's home Fortress to await their next deployment.
These Knightly Orders, alongside their equivalents in the other Kingdoms, were disbanded by the Vytal Peace Accords. Their ancient Fortresses were pulled down and used as building materials for a modern City of Vale, and the rolls containing the names of their former members were solemnly burned in the courtyard of the old Valean Royal Palace on the day before it became Beacon Academy.
Whilst the idea for the Association was tabled and even agreed upon during the Vytal Treaty Debates, it was not formally created until after the dissolution of the Kingdom of Mantle. On the first day of 14AW, an amendment to the VPA was agreed upon by all signatories, and the Huntsfolk Association was born.
Legally, the Association is an independent entity. According to its founding decrees, its members cannot be used to wage war or commit acts of espionage or assassination on behalf of one sovereign nation against another (or on the behalf of a non-sovereign entity against a sovereign one). Huntsfolk are free to travel the world without passports (so long as they have their licence), and complete missions in each Kingdom regardless of their nation of origin. In theory, Huntsfolk are supposed to be loyal to Remnant and all its peoples, rather than just the nation of their birth.
In practice however, and perhaps unsurprisingly, the majority of Huntsfolk do remain loyal to their home nation, even if they adhere to the rest of the Association Decrees.
As an Atlesian citizen and member of the Military, I would be remiss if I failed to mention our 'Specialist Program' at this point. Whilst they are still technically members of the Association, the Atlesian Military 'hires' them as what amounts to outside contractors to serve within the Military as a sort of 'specialised combatant', hence the name. The fact that students at Atlas Academy are all but encouraged to join the Specialists after graduating is a complicated grey area that is pretty much ignored by the rest of Remnant, although does often get brought up in times of political and diplomatic unrest.
Whilst it is officially headquartered on the island of Vytal like most international institutions, it is primarily staffed by the Association's administrative workers, with a small cadre of active Huntsfolk to act as security for the entire island. Each Headteacher of the Four Academies is also the Head of that nation's branch of the Association. In this role, they are responsible for ensuring the safe and sensible distribution of field missions, along with the fair payment or reward for the completion of said missions. They are also responsible for the pension scheme of all members of their branch, and for arranging for and ensuring Association representation at the funerals of any members that die in the line of duty, should the fallen Associate have requested a Huntsfolk Funeral.
Each student that attends one of the Four Academies (Beacon, Haven, Atlas and Shade.) is granted a Provisional Licence automatically upon successfully completing their initiation. Assuming that they graduate, this licence is upgraded into a full one. Students of the various feeder schools do not receive a licence of any sort, and expelled students have their licences revoked in the same manner that those that violate the Association Decrees would.
The Association is not without criticism however. It is the only legal way through which Huntsmen and Huntresses can gain licence to take and complete legitimate contracts and missions and receive the rewards for their completion. In the past it has been accused of being overly heavy handed with those non-Association Huntsfolk seeking work, even outside of the usual channels. Indeed, until as recently as 60AW, the Association would regularly seek the arrest and detention of any person completing missions without one of their licences and was often successful (at least outside Vacuo, because honestly, not even the Vacuans can tell the Vacuans what to do).
There are presently no provisions for if a new nation is both formed and gains the right to have an Academy, although it is assumed that a similar system to the ones already in place in the Four Kingdoms would be installed. In all likelihood, the next time this will happen is probably going to be if and when Menagerie gains Kingdom status.
Whilst I must confess my overall knowledge about the Association is limited to what is publicly known, given my impending career change I am certain I will be gaining an more indepth knowledge of this organisation. Whether that will be a good thing or a bad thing remains to be seen..