Eric, are you sure about this?
I found this:
"All users of wireless microphones may operate the equipment on an unlicensed basis, subject to certain restrictions: the device (1) must not be operated at a power level in excess of 50 milliwatts, (2) may not cause harmful interference, and (3) must be operated in a way that accepts any interference that may be received. For most users – such as theaters, churches, schools, conference centers, theme parks and musicians – the use of this device is unlicensed."
Here