Here’s a report <https://www.theregister.com/2022/09/30/citrix_xen/> on a talk by the software development manager at Citrix, detailing the ups and downs in the history of their Xen hypervisor. Initially they had a “freemium” model, with an open-source “community” version and a proprietary paid “enterprise” version with more capabilities. This worked well and brought in sufficient revenue to be sustainable. Then they decided to switch to make the “enterprise” version open-source as well, relying on customers’ willingness to continue to pay maintenance rather than support the code themselves. This bet failed to pay off, and revenue crashed. On the other hand, Citrix did not include the “accompanying tooling” (not sure what they mean here -- build tools? Add-on admin tools?) with the source code, making it hard for others to use that code. (Were the big “enterprise” users the ones able to figure that out?) Then they tried to go back to a “freemium” model, with restrictions being imposed on the open-source version. While this did restore the revenue stream, it also antagonized a significant part of the community that had been using the open-source version in various unusual and creative ways. These users forked the code to create XCP-ng, leaving Citrix behind. I suppose the lesson to take from this is that “freemium” works, but it is best if you do things that way from the beginning: trying to switch to it (or switch back to it) from an all-Free model can be painful.