Hey there Lexie,
Welcome to planDisney and thanks so much for your question! First, it sounds like you're an amazing friend - buying a one-day ticket to the Disneyland Resort is such a nice gift!
In terms of the expiration date for your ticket, the best place to check is the confirmation email you received when you purchased the ticket. You should be able to find it in your inbox if you search "Disneyland Confirmation" and the expiration date will be called out about midway down the email.
According to the
theme park tickets purchase page in the terms & conditions at the bottom of the page, one-day tickets purchased through Disneyland.com or the Disneyland app today are valid now through December 30, 2024. As long as you purchased standard theme park tickets for your friend, I'm guessing this will be the same expiration date for that ticket as well. However, again, I would double-check the email confirmation you received to confirm.
If you can't find your confirmation email or still have more questions then I'd recommend
calling a Cast Members at the Tickets line! They should be able to help look up the ticket and confirm all the details with you over the phone.
I hope that helps - thanks again for your question, Lexie!
Have a Magical Day,
Greg