In terms of distance, If you shoot a laser from a laser source, it'll continue to travel in the air unless hit by an obstacle. That's because the laser's single wavelength helps a laser cut through the air molecules without getting scattered. Regarding duration, most lasers are powered by alkaline batteries, which can power a laser for an hour or two. The actual duration of a laser depends on the battery capacity. The silver dioxide and lithium-ion batteries can continuously power up a laser for more than 6 hours.