Depends entirely on what frequencies you are using. There is no one license that will cover all the frequencies these radios will work on.
The type of license you need really depends on what you plan to use the radio for.
Amateur radio is great for making random contacts with strangers. There are allocated slices of spectrum in many places, but for these radios you'd be able to use the 2 meter VHF and 70 centimeter UHF bands.
GMRS license is more useful for family use. There are some dedicated UHF frequencies availlable.
A business license would be good if you were using the radios for your business.
Licenses -only- come from the FCC for these sorts of applications.
The type of license you need to apply for will depend on what you want to do. The licenses for amateur, GMRS and Business use are all different.
Amateur radio requires taking a 35 question multiple choice test covering amateur radio rules, operating practices and some very basic radio theory. The amateur radio license ONLY covers you, no one else. Each person using the radio on amateur radio frequencies will need to have their own valid FCC amateur radio license.
GMRS requires paying a license fee, filling out a form, and waiting for the license to be issued. The GMRS license will cover you and your immediate family (not friends/neighbors/co-workers, they have to get their own license)
Business licenses will depend on what you are doing. There are "itinerant" licenses for simple use. Some frequencies will require the services of a frequency coordinator to help you find suitable frequencies that are available in your area. The license will cover you and your employees.
You might hear about "MURS", Multi Use Radio Service. MURS does not require applying for an FCC license. Problem is, these radios do not have the proper FCC type certification for use on the 5 MURS channels. Legally, you cannot use them there, although some people do anyway.
