The tip does not expire in the sense that it just goes away. The tip must be cancelled before its expiration date and if that isn't done, there is NO WAY you will be able to get a new one and furthermore, the boat MUST be removed from Mexico or it will be impounded. If there is any chance that the present owner can't or won't go to aduana to cancel the tip, then DO NOT HAVE ANYTHING TO DO WITH BOAT!!
Is Power of Attorney Letter from TIP owner can do magic?