I own a one-man company, and design/develop imaging systems for industry.
One of my customers commissioned me a project in the field of medical science quality inspection, for which I designed the hardware system, the software algorithm and developed the software user interface, so that he could build an automatic machine doing that quality inspection job on the production.
Given that the field of application of this particular system is very unique, the customer is asking for exclusive use of the software. Unfortunately he is quite unreliable in terms of payments, but I'm interested in selling the software, I'm searching for help in writing a good contract, such that I can provide him with exclusive use in change of a minimum number of copies per year, but at the same time I can own any propery on the software and can decide to cancel exclusivity in case of the minimum budget was not fullfilled. If you need more informations please ask.