What's the notice period on the contract? If its a minimum 12 month with no notice, then the cost of the ticket is a recoverable loss if the client breaks the contract (by termination, for any reason).
Fixed for 6 months? Same as answers above; build the cost into the fee.
Is it a rolling n month contract? Either within the contract, as an addendum that is mutually agreed, or as part of the schedule, have a clause added that in the event of a termination for {reasons} or {not reasons}, the client will refund the unused value of the ticket. (They may refuse to change the contract, as those are usually very legally specific, and expensive to alter).
You could do this instead by requesting a Letter of Intent (i.e. the client intends to retain your services for the duration). If the client has confirmed they definitely want to retain you, and yet refuse to write such a letter that should tell you something.
In any case I would question the wisdom of buying a 12 month ticket. What if you lose it? Can it be easily / freely replaced? I've almost always had weekly tickets myself, and was very glad (that it was only weekly) when I lost one the day after purchase.