Closing time was the time at which an establishment shuttered its doors for the day.
In 2373, Tuvok cited a witness who claimed to have seen Nakahn's lights on after his usual closing time, less an hour after an attack on Zahir. Nakahn claimed to have been working late, while the Vulcan suggested he was paying the person he hired to assault Zahir. (VOY: "Darkling")
In 2375, "Valerie Archer" told Chakotay that it was the Quantum Café's closing time. (VOY: "In the Flesh")