A license holder is not obligated, required, or mandated to engage in the licensed activity. A license regulates the practice of an existing ability. I could have a driver's license and take the bus. That does not mean a driver's license is not about driving though.
A Marriage license regulates the existing ability of most male/female couples to procreate. A Marriage license promotes "responsible procreation" in the same way a driver's license promotes "responsible driving".