Tohru even says that the world Kobayashi lives in is low in mana, so it's likely that the dragon's life span comes from that, and that without it, they will age as other humans.
Ratana is such a tease, but it keeps me buying coins. Didn't think I would be literally throwing my money at her (bought and will buy Lily Love and Pulse and whatever else the woman creates at this point), but it's worth it. : D