With pay-per-use systems, you charge for every time the system is used. Money is the ultimate feedback. Not only is it concrete, you can also spend it. Connecting money flow directly to software development provides accurate, timely information with which to drive improvement.
Lots of software is already pay-per-use. Telephone switches, electronic stock exchanges, and airline reservation systems all charge you a fee per transaction. While pay-per-use has business advantages and disadvantages, the information it generates can help improve software development.
The ultimate form of pay-per-use I've seen was in a messaging product. Users were charged per message. Each story in development was deliberately selected to encourage more messages. Support for a new handset, for instance, came with both a cost estimate and a revenue estimate. The team analyzed the usage of the system to provide feedback for the accuracy of the revenue estimates. The team used this information to optimize both cost and profitability.
Today's typical arrangement requires the customer to pay for each release of the software. Pay-per-release opposes the supplier's interests and the customer's interests. The supplier is selfishly motivated to have lots of releases, each containing the least possible functionality necessary to get the customers to pay. The customer wants fewer releases (because of the pain of upgrading), each containing lots of features. The tension between the two sets of interests reduces communication and feedback.
Even if you can't implement pay-per-use, you might be able to go to a subscription model, in which software is purchased monthly or quarterly. With the subscription model, the team at least has the retention rates (the number of customers that continue to subscribe) as a source of information about how the team is doing. An even smaller change of business model is to weight contracts more toward support fees and less toward up-front revenue.
One objection to pay-per-use is that customers want predictable costs. If the price advantage of pay-per-use is large enough, customers may not mind. A team using the information provided by pay-per-use should be able to do a more effective job than a team relying for feedback only on license revenues.