DaVinci Resolve (a very popular Color correcting and video editing software) is needed to work effectively with some of the ProRes Color schemes. Its basic version is free but there are paid upgrades to it. This app is likely a funnel to their software and other peripherals
Blackmagic also sells a lot of hardware. They may not be making money directly with this app, but they are going to earn loyalty.
Another comment earlier mentioned how Davinci resolve may start gaining market share for the very reason that it's free and kids learning to edit are more likely to go with them instead of cracking adobe these days (and then using the former when they enter the workforce).
i didn't see a pro/paid version - unless they're planning to offer a post-processing cloud subscription later on...