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.
What is a king to do? A prophesy indicates that a certain person is involved with the death of the king, but the prophesy was unclear as to what role - do they cause it or prevent it.