If I purchase a Maglev Round Trip + Metro One-day Pass, must I make the return trip 24 hours later?

Planning to visit Shanghai for 3 days and purchasing the Maglev Round Trip + Metro One-day Pass as I am planning to use the Maglev as transportation to and from the airport. Can I use the roundtrip ticket 2 days later, or must I use it within 24-hours? If this is not possible, are there any tips on what kind of ticket I should purchase for a 3-day trip in this city?