Hypothetically, if there were a community of Hintergnomes in Vralkast, they would be the creators of the Hinterpocket. They would also form a regulatory body, a Hinterguild of Pocketers and Bagmakers, to regulate the creation and sale of these pockets. Individuals would then need to be licensed (sanctioned) by this guild to sell these pockets on their behalf.
Unfortunately, Hintergnomes don't exist. However, this merchant is luckily fully licensed by the Hinterguild and can sell on their behalf!