In this episode of "Your Drone Questions. Answered", John Dickow is joined by Kara Murphy, a commercial drone pilot, photographer, writer, and contributing writer for DP Review. 
The episode covers the question of what license is needed to make money with a drone. Kara mentions that to make money with a drone, one needs to pass the Part 107 Exam, which enables flying for profit.
Failure to obtain the certification can result in fines of over $30,000 per violation. The exam is not something one can cram for, and passing it requires knowledge, which needs to always be improving. Kara also discusses the difference between the Part 107 exam and the recurrent exam, which pilots need to take every two years.