While we're on the topic of licenses, check your state's regulations. I've hunted in 4 different states, and in each state, one must buy a new license every year (unless they have a program for veterans to buy a lifetime license, etc.).
Each game animal you hunt will have certain dates you're allowed to hunt them in ("season"), and limits on how many you can harvest.
You may need multiple licenses, too. If you hunt deer, that's usually one license. But if you hunt rabbit, squirrel, and other small game it will be another. If you go after ducks and geese there are additional licenses or stamps for your licenses you must buy. You get the idea. Check your state's regulations, as each place is a little different. Most states print an annual paper manual explaining their state's hunting laws and give them away for free at places that sell licenses.
Lastly, some big game licenses (including deer) are done by a drawing system. In these states, one cannot simply walk in and buy a deer license the day before season starts. There is a drawing process for the licenses MONTHS in advance. Other places like Virginia let you buy a license any time you want. Check your state's regs and be prepared!
The bottom line, I suppose, is CHECK YOUR STATE'S REGS!