That depends....
Some tickets expire the night of purchase, but most tickets do not expire.
If you purchased the tickets with ANY discount at the PI Ticket trolles (AP, DVC, CM, DDE, Coupon, or Hospitality ) - then yes, they expired the night that you purchased them.
If you paid full price for the tickets, then they do not expire until when you use them. If you purchased them online, or from an off-site ticket vender, those also will not expire until used.
They can check to see if the tickets are expired at any Guest Relations location, or at the PI ticket trollys. Although if there is a line at the ticket windows, you can also just find out "the hard way" and just go to a club and see if that work. However, if you're confident that you paid full price, you should be fine.