Golden tablets with the seal of the ruler that issued the pass and the seal and name of who it was issued to. About the size of your palm of solid intricately etched gold. The holder of the tablet is backed by the authority of the king to make any required purchases on credit or enter any place they deem necessary. A very powerful token indeed.
It is said that though the crown has always been passed through inheritance, no man may rule without the approval of the Archmage and the Guildmaster. (Interpretation I leave to interested parties.