If you are, in fact, moving to a WDW resort, after being off-site, I would keep the rental car and make the move to your WDW resort with it. Then return the car to either the CCC or the Dolphin or one of the DTD car rental agencies. Then, sign up for DME for your return to the airport after your WDW resort stay. But, if you aren't staying on-site at WDW, then you can't use DME at all.