How long astronauts stay on moon?

Apollo 11 landed on 20 July 1969 and lifted off less than a day later, after a single moonwalk of about two and a half hours; the flight plan treated the surface as a place to prove that a landing could be survived. The later missions were designed for science. Apollo 15, 16 and 17 carried an extended Lunar Module with more propellant and consumables, plus a folded rover, and each stayed about three days. Apollo 17 set the record at roughly 75 hours, with three separate excursions away from the lander.

The constraint was never the astronauts but the lander. The Lunar Module carried its own oxygen, water, batteries and cooling supplies, and every extra hour on the surface meant more mass launched from Earth. Lighting mattered too: Apollo landed shortly after local sunrise, when long shadows gave the crew depth cues and the ground had not yet heated up, and since a full lunar day lasts about a month, waiting out the night was never an option. Dust was a third limit, abrasive and clinging, hard on seals and suit joints.

NASA's plan for the first Artemis landings is a surface stay of about a week near the lunar south pole, with a crewed lander derived from a much larger vehicle and suits designed for repeated use. The south pole was chosen for ridges in near-permanent sunlight and shadowed craters holding water ice, and both point the same way: stays measured in weeks rather than days only become practical once power and consumables come from the Moon itself rather than from the lander.