Really? I didn’t know. To me it seems like a ticket expiration question. I’m really just wondering when package tickets expire, if the package was booked 10/17 but check-in is in 7/18. I should have been clearer maybe?
Since you were so specific in asking about a "free dining package ticket" I figured
you wanted to discuss if the dining credits expire.
If what you want to know is when
currently-purchased park tickets will expire, that would normally be Dec. 31, 2018.
However, it MIGHT be that the tickets you will be issued in 2018 MIGHT be tickets from a time after an upcoming price increase.
If so, it is possible that those tickets MIGHT have an expiration date of, say, Dec. 31, 2019.
We just don't have enough info to know for sure.
Regardless, unused tickets that "expire" still have some value.
After expiration, their original value price can be used to help defray the cost of purchasing new
tickets, at such time as you make a future WDW trip.