Off Reservation - If the supplier is providing goods and services to an EWO, LEWO, or FSCO off-reservation then there is no dollar threshold and a license is required.
On Reservation - If the supplier is providing goods and services on-reservation, the supplier will need to be State Certified as a gaming vendor. More information on the on-reservation certification process can be found on this page: https://gaming.az.gov/tribal-gaming/state-certifications