I just released the beta version of the site so I don't have any data-points yet. But I'm hopefully going to bank on enterprises mostly purchasing the software, and those are going to be entities that I know will most likely respect the per-user contracts. The entire source-code will be available to the customer once they purchase the license. I've had to make a lot of hacks when tailoring 3rd party software with pieces of their code closed-source, so I hope to alleviate that pain for other developers.

What type of software do you sell, and how are you currently charging clients?