why does he save our snapchat conversations?

There's a guy that I like. We started off being friends online for probably about 7 years. We haven't talked in about three and recently reconnected on Facebook. We have hung out once in which time we talked non stop for about four hours, then we hooked up. We didn't have full on intercourse, but we made out and gave each other oral. Anyway, he's very wishy washy and I can never tell if he's truly interested or not. 🙄 I DID used to friend zone him often back in the day because I wasn't interested in him romantically back then. We snap back and forth a lot, both videos/pictures (never anything sexy) and flirt a lot. But I noticed that he is saving all of our conversations, including both his response and my responses. I don't understand why he is doing this as no one else I snap with does this. Any insight...?