Probably, but it depends on the state(s) in which your customers are located. Travel agent licensure/authorization in the US is governed by state law. In California, for example, the California Attorney General's Office administers the Seller of Travel Program: https://oag.ca.gov/travel

Start by figuring out where your customers are located, then you can research each state's law. Here's a starting point: http://travellaw.com/page/travel-law-faq