If you have a expired tickets (a 3 day ticket for example) with remaining days left you can make FP+'s. I was trying to see maybe if you could do this, and you can. To go into more depth, the ticket, will unfortunately expired. But you do get more FP+ reservations. I have an annual pass however I went on a trip with 2 people who weren't and they both bought 3 day tickets and because we didn't use the third day, the ticket itself expired, but their was one day left for FastPasses(+). Thought this may help anyone take advantage of this.