Its just like those ISBN numbers you have to buy when publishing a book.
https://www.48hrbooks.com/options/isbn?gclid=Cj0KCQjw753rBRCVARIsANe3o467GFGxDcoP4c55vKhkyEyKCCuRqg5v-RaJzAxxm7kRDmxVgPX_vpYaAi12EALw_wcB
I ran into that issue years ago when I self published my novel.