Just be on the lookout if he seems to be doing such things. Can you say the same? Whenever you move in with someone, make sure there's an exit plan where you know you can afford to get out on your own.
For example, if you two had a fight - if he wants to leave and stay in a hotel for a week, he may be able to afford that.
There is a power imbalance that comes from him being older and having saved some money. Same idea as above: he may try to influence your life - what clothes you wear, what job you have, where you live, your sexual relationship.
They use the power/age dynamic to their advantage. It can seem fun at first for you, but you may notice that as you get older and gain maturity, he stays "stuck" at an emotional age of 21. They know that a woman their age will notice this and either not enter a relationship, or call them out on it. Men who are dating quite younger women often fall into two (or both) groups: Not saying this is all relationships with this kind of age gap, but it does happen a lot.