FiLMiC Pro, another pro camera app for iPhone, also existed for years [0] and sold with the one-time-purchase business model. They're now a subscription [1] and owned by Bending Spoons / Evernote. (Plus, more bad news [2]...)

[0]: http://web.archive.org/web/20111130073123/http://www.filmicp...

[1]: https://www.cined.com/filmic-pro-is-joining-forces-with-bend...

[2]: https://www.theverge.com/2023/12/3/23986187/filmic-staff-lai...