Freelancing is a business. Like any business, you need to pay taxes.
Depending on how you register your business, you might not need a business license.
Your social security number is your license if you are a sole proprietor. That means you can file your taxes yearly, the same as you do when you're an employee.
You can go to an accountant and have them file your taxes to make sure you take advantage of any credits available to you. The most important thing for you to do is keep track of your expenses and your income.