Check the date on your tickets. Tickets purchased before January 2, 2005 will be honored, according to Walt Disney World Resort. Tickets purchased before this day were bought before the new pricing structure went into effect and are still accepted at Disney.
Check your tickets or receipt if you purchased your tickets after January 2, 2005 to see if you purchased the "No Expiration" option. If so, your tickets will not expire and you can redeem them at any time.
Check the date you last used your "Magic Your Way" tickets. If you have never used the tickets, you can go at any time to use them. If you have used the tickets before, and did not purchase the "No Expiration" option, your tickets will expire 14 days after the first use.
Contact Disney through their website or on the phone if you are unsure about your tickets. They can tell you the specifics about what you purchased, or are planning to purchase, and how long they last.