Originally Posted by USCGamecock
I think you only have to use it by the expiration date. If you buy a refundable ticket, then you could use it later towards another ticket. I'd call DL and ask.
I am not sure what happens if you decide to change the date/city pairs and the Delta dollars had already expired. I know it will work for booking the first flight prior to the expiration date of the Delta dollars. I believe that you may be out of luck then.