In our state, bingo is considered "gaming" and is regulated by the State Gaming Board. When we decided to do a family bingo night, we got a copy of the standard gaming license. We were shocked to read that no one under age 18 could be involved, but we called the office directly because the application was a little ambiguous. When we thoroughly explained the format of our event, we were cleared, no license required and kids could play. I don't remember all the specifics that made our fun family bingo night legit, but I assume the rules vary from state to state. Check the rules for your state, and don't be afraid to call the authorities if you have questions - especially if you're setting it up as a fundraiser. Ours was just a fun night out.
For an adult bingo fundraiser you just need a license from your state & city/town. Try a google search for bingo license/your state and you should find information. You can also go to your city/town hall and the clerk there should also be able to help you get a license. It is just a matter of paying the licensing fee and filling out some paperwork.