We also use community vials and charge through Pyxis.
As a check and balance, when the pharmacy techs do daily Pyxis fills, they check insulin vials, expecially the ones found on the counter or on top of the Pyxis machine, for dating. They take any vial that has no date. It is replaced to the floor and charged to the floor, as well. Some think having the floor pay for an undated vial reminds them to follow procedure--I'm not so sure about that.