If there's no ongoing payments, then support only provides passive sales. It can only turn disgruntled users into advocates, and reassure people that it's safe to recommend the product to others. Never discount, however, the ability for high quality support to make a great part of any sales pitch!
But when there are oportunities for ongoing payments, especially in the case where these are actually for service support (and they often are), the quality of your service support is what will be looked at when it comes to renewing the contract. And if there's no contract, the quality of your service support is the only thing standing in the way of them switching providers (unless you've implemented some type of lock-in).
From a service support point of view, the real question is does the sales force actually talk with the support team? A contract that can't be met isn't profitable.
But when there are oportunities for ongoing payments, especially in the case where these are actually for service support (and they often are), the quality of your service support is what will be looked at when it comes to renewing the contract. And if there's no contract, the quality of your service support is the only thing standing in the way of them switching providers (unless you've implemented some type of lock-in).
From a service support point of view, the real question is does the sales force actually talk with the support team? A contract that can't be met isn't profitable.