Generally, you need a "license" when you need special permission -- like a license to practice law or medicine. There's usually no special "license" needed for graphic or web design. However, if you are doing your freelance work under a name other than your own -- for example, "Robin Smith Graphics" (instead of just "Robin Smith"), you will have to file a business certificate with the local county clerk.
Confirm with an attorney in your state to make sure you're following the rules properly.
Creating a MAP will take no more than an hour of your time every month and will keep the lines of communication open, ensuring relationships with investors remain strong, and ultimately helping early-stage startups succeed.