That means the payer is getting something else besides the right to use the patent. So whatever product or service the payee is providing, they have to continue

That means the payer is getting something else besides the right to use the patent. So whatever product or service the payee is providing, they have to continue providing it even though their patent is invalid. That doesnt seem like such a problem, except for the fact that when the contract was drafted, there may have been less competition for the service the payee offered.