> What I do take issue with, however, is convincing everyone that your product is FOSS, waiting until people undertake a lot of work to integrate your product into their infrastructure, and then doing a bait-and-switch.

But FOSS means “this particular set of source files is free to use and modify”. It doesn’t include “and we will forever keep developing and maintaining it forever for free”.

It’s only different if people, in addition to the FOSS license, promise any further updates will be under the same license and then change course.

And yes, there is a gray area where such a promise is sort-of implied, but even then, what do you prefer, the developers abandoning the project, or at least having the option of a paid-for version?