Typically they always use wording like that. As long as the ticket is still unused they will at minimum let you apply the value to a current ticket. I've never heard of a situation they would not issue some type of credit for an expired ticket that did not get used.
The big thing is only 1 to 1. The credit from one ticket can only be applied toward one current ticket. So you cannot apply 3 unused
MVMCP to a 5 day hopper, or apply a 7 day toward more than one ticket of any kind. They also will not refund any difference if your credit is larger than the new ticket desired.