The purpose of a queen to maintain the viability of the colony. She will lay up to 2000 eggs per day, out of these are a mixture of fertilised and unfertilised eggs. The fertilised eggs become honey bees, unfertilised eggs become drones. The longer term success of the colony depends on many factors, but the important one was the success of her mating.
A virgin queen emerges from her cell 15 days after the egg was laid. During her second week of life she will mate with up 15 drones while in flight. The drone dies immediately after mating occurs. The queen will store the semen from the drones and will not mate again for the rest of her life even if she runs out of sperm. If she runs out, she will lay drones.
If the queen is unable to mate over a period of time because of bad weather or it is too cold, she will lay drones for the rest of the colonies life. For without honey bees the colony is unable to maintain itself, the bee population declines and eventually the colony dies out.
This image shows a drone mating with a queen.
Copyright WGBH Educational Foundation (http://www.pbs.org/wgbh/nova/bees/making.html)