The legal answer is: You need to test, and submit a test report, to the FCC under part 15. Then they will give you a FCC ID number that you can use to sell the devices.
You may be able to use someone elses printed wiring board design, with the nordic chip on it, who has already submitted their design for a FCC ID number.
Techinically, it is not a license…you can use it anywhere in the USA. You are just verifying that it meets the limits for “unlicensed” operation.
The test report makes sure you are in the right frequency band, the transmit power and harmonic power is low enough, and you are using the correct modulation spectrum.