No, there is no limit of ages. If you a fan of harry potter, you shall still remember the harry potter always wear the round eyeglasses whenever he is kids, teenagers and grow up. So, you can wear harry potter round glasses. And the only thing that may limit you is your face shape and facial features. That because not all people can get good looks in simple designed round glasses. So, just try on and test it out yourself.
Of course. round glasses are suitable for men who are over 30 as long as they look good on you. There are many middle-aged men who are over 30 prefer wearing round glasses. round glasses have become popular not only with teens but also middle-aged men these days. If you love the potter style round glasses, you can try them on first and see whether they are suitable for you. I believe they will look good on you.