How do I drop hints to my boyfriend that I want a promise ring?

S • 💏💑😍
We've been together 6 months now. And I'm not saying I want one now but sometime in the future if he does plan on marrying me ( which from past conversations he does) I want a promise ring especially since he goes off to college and it just would show a commitment to me. Not saying I need one but I'd like one.