22 year old son taking advantage or being taken?

My 22 yo had just three courses to graduate college. He was offered an opportunity to work at a financial firm in NYC (no paycheck) but this firm prepares students to take the Series 7 exam. I checked the firm out - it is legitimate, however I'm suspicious it's taking so long to prepare for this exam. I'm covering his expenses, but it's getting frustrating. He insists he's almost ready, but it's now been going on 5 months. Does anyone have any insight to this type of scenario and whether if he does pass the Series 7 test, are there possibilities for him to be gainfully employed or is it a scam?