Where can you get a jet ski license?

Laws vary State-to-State so you should check with the agency that governs boating laws in your State. The National Association of State Boating Law Administrators approves courses at the national level and most States follow those guidelines. States have final approval and subsequently approve courses that yield a Safety Certification (what you refer to as a License). Both in-class and online courses are available dependant upon what your State approves