The simple version of Prison commissary.

A prison commissary or canteen is a store within a correctional facility, from which inmates may purchase products such as hygiene items, snacks, writing instruments, etc.

A prison commissary or canteen is a store within a correctional facility, from which inmates may purchase products such as hygiene items, snacks, writing instruments, etc. Typically inmates are not allowed to possess cash; instead, they make purchases through an account with funds from money contributed by friends, family members, etc., or earned as wages. Typically, prisons set a maximum limit of funds that can be spent by each inmate on commissary.