The Middleman Retirement Ceremony is a seldom-seen event in which an active Middleman retires from the service of O2STK. Its description as "seldom-seen", and a comment by Clarence Colton that "a Middleman who makes it to retirement is breathing rarified air" suggest that the vast majority of Middleman are killed in the line of duty.
The ceremony includes the expression:
"Let this Middleman, this sword of the people, rest in the fond sheath of retirement. Sharp is the justice he did once and will forever champion."
followed by the Latin Pugnantos Malos, Nehos Pugnetis. Optionally, the person conducting the ceremony can read a composition. The ceremony concludes with the presentation of a gold watch to the retiring Middleman, and the Middleman's formal statement (and reassumption) of his or her given name.
The only Retirement Ceremony depicted in the series is that of Guy Goddard, the 1969 Middleman. It was conducted by Clarence Colton. Presumably, since there is only supposed to be one Middleman and one Middle-Associate, a normal retirement ceremony would be conducted by the Associate, who would at its conclusion become the new Middleman.