A medical marijuana business earns by selling marijuana to patients. The business can operate legally if the owner obtains proper medical marijuana business permits and operates in compliance with the laws. 
Depending on the state you live in, you can grow your own marijuana and sell its products to increase your profits. But, there are some states where marijuana has to be purchased from licensed growers and resold on the market. The exact laws that apply to the kind of business you can actually set up varies from state to state. This is the reason it is crucial to be up to date with the licensing procedures in your respective state before you even consider applying for medical marijuana business permits.
By having proper permits in place, you can avoid getting into legal troubles. Always remember that marijuana in an illegal substance under the federal law and if you don’t want to face prosecution or end up paying hefty fines, then you have to stay in compliance with the laws. When it comes to making applications for permits, it always helps to seek legal advice. This way, you can keep up to date with the laws and learn the techniques that successful businesses use to stay away from federal problems.