give away would be literal, but in "legalese" forfeit seems more appropriate

I take it this means that the concessionaire of a motorway, say, cannot sell or transfer by any other means the right to collect money from motorists to any other party. Presumably there would be some sort of user-tariff agreement between the concession authority and the concessionaire, in the interest of the user, that would not be binding on a newcomer were a newcomer to be allowed in on the act (without the approval of the concession authority which would, presumably, in any case, set up a tariff agreement with the newcomer).