Hi Jonathan, welcome to planDisney!
Thanks for bringing your question to us, I'm happy to help!
Looking up your ticket's expiration date can be easily done through the
Disneyland Mobile App! Just load up your Mobile App, click the three horizontal lines in the bottom right-hand corner and select "Tickets and Passes". You should see your tickets along with their expiration dates!
If your tickets happen to expire, you still have options! Per
Disney's eTicket Terms & Conditions, any wholly unused, expired Disneyland Resort theme park tickets (except for special event tickets or tickets purchased from a third party), can be applied towards the purchase of a new theme park ticket in equal or greater value to what was paid for the original ticket!
I hope this helped, but if you have any more questions, you know where to find us!
See ya real soon!
Jin