Hello Joe,
If I understand you correctly than you are paying the maintenance fee and therefore are entitled to installing any updates for domino. In this case, you made sure you are entitled for installing Domino 9.
I don't know of any license model which would not allow you to install/update your traveler server in a current version. But in doubt you are better of asking your IBM Partner, who sold your licenses.
There is no need to do anything on client side, when you perform a simple in-place-update.
Hope that clarifies it,
Manuel