The ability to change the address on a drivers license for free varies by state, because each state has its own Department of Transportation, with its own rules. States can allow unlimited free changes, one free change for a set period of time, or they can charge each time.
For example, Pennsylvania and New York allow for free address changes, Georgia allows for one address change every four-year period that a license is valid, and Florida charges a fee for every change of address. These changes can be done online, on the state's Department of Motor Vehicles website. A camera card or new license is then mailed to the new address.