As long as you're just boondocking or using it on your own land or something it's not required, but legally if you're plugged in to electricity and it has an LP system and you plan on sleeping in it, it has to be certified as to the 'life safety' systems such as electricity, LP or gas, and the LP, CO, and or smoke detectors.
If it looks like a factory unit you might fly under the radar, but don't be surprised if campgrounds won't rent you a site for your "2017 Mako Kupo" brand RV. They won't want to risk issues for a few bucks rent.