Without looking this up in the Instructor Manual and without calling PADI (lazy, I know), I don't know if the AOW program dives have a time limit (like the 12 month OW referral limit). IF they do, then it would be reasonable for someone, with a limited about of time and/or money, to do the 3 Adventure dives and get the card. At a later time, clearly without a time limit, they could "upgrade" to AOW just like a Scuba Diver can "upgrade" to OW without the 12 month referral issue.