Business licensing is up to your state/county/city government. Ask your CPA. Usually the license fee is significantly less than the fines for not having it if you are required to be licensed. A small startup like yours that can be classified as a hobby may be exempt. If your CPA isn't sure, call city hall or check with the SBA (small business administration) for more info.

First goto: http://www.business.gov/register/licenses-and-permits/ There you can see what permits and licenses you might need to legally operate your business in your state and county.