We recently closed on two resales. Both were purchased through The Timeshare Store and in both cases the 2042 date appears on the Purchase and Sales Agreement.
More specifically, in the case of the Agreement The Timeshare Store uses it appears in Paragraph (2) which states "Seller shall convey DEED, EXPIRES 1/31/2042 to buyer......"
I would think the Agreements from the brokers most often mentioned on this board would be substantially the same. If you can't find it there a call to the broker will provide the answer you need.
Good luck with your resale.