We're going down in November and will be buying 7 day MYW tickets. I don't think we will use all the days. Can I upgrade to no expiration my last day there and only pay to upgrade the days I didn't use? In terms of budget, the tickets for 4-7 day MYW cost the same so I might as well get the 7 day, but I'm certain I'll be wasting a day or two if I don't upgrade.