Most female reptiles can store sperm for weeks, months or even years.
Storing sperm allows females to fertilize and lay eggs when climate and conditions are favorable, increasing the likelihood of success for their offspring. This has many interesting consequences, including the possibility of multiple fathers for some egg clutches. Multiple fathers would increase the genetic diversity of her offspring and could be an advantage, especially if environmental conditions were changing. In some cases, sperm from multiple males will have to compete for egg fertilization, increasing fitness of offspring. Sperm storage also means that a female does not have to settle for an inferior male if she had previously mated with a superior male.
Among vertebrates, turtles and snakes can store sperm for the longest periods of time. A recent scientific study has documented proof of fertilization in an Eastern diamondback rattlesnake snake 5 years after mating! http://www.newscientist.com/article/mg21228355.200-snake-stores-sperm-for-five-years-before-giving-birth.html
What does this mean for the pet reptile breeder? Clearly it is something to keep in mind if you have a breeding program planned. Leopard geckos can store sperm for up to 1 year; bearded dragons for several months. If your female bearded dragon has been with more than one male, the paternity of her clutches will be in doubt.