When someone puts a significant and useful software under an open license (like BSD) and nurtures a vibrant open-source community around it, sure, everyone else can definitely take it and use it for free. But nobody serious will use it just because it is free. They will consider other intangible but critical aspects like risks to themselves w.r.t future viability of the project, ability to get custom work done to it or around it, keeping up with hardware and software ecosystem trends etc. These things have second order implications – how healthy the broader developer ecosystem is, is there a broad base of core committers we can hire, how easy it is to upstream our changes, who else is using it at similar scale, criticality, cost efficiency; is commercial support available (sometimes 3rd party commercial business support ecosystem is essential due to regulatory/compliance reasons), do hardware vendors actively participate in the open-source community and ensure it runs well on their hardware etc.

Apart from free users, even the contributors have very similar considerations for their participation.

But the starting point is the license – it has to be a clear and unambiguous open-source license that is widely well-understood – especially w.r.t the blast-radius or infection radius of the license. Does it infect the library code that is linked/loaded into it? Does it infect the independent binary/processes that scaffold around it (say, control-plane, orchestrator, proxy etc)? What are the obligations if it does? If we have to get lawyers involved to answer these questions because it is a custom license that is vaguely written or it has never been challenged in a court or the license holder is of unknown reputation, these are huge red flags.

Another equally important consideration is the motivations of the stewards of the project. While this isn't explicitly stated, one cannot be naive about it. Contributors and users will have to consider a gamut of scenarios – best/base/worst scenarios and make their judgement. With smaller steward organizations, there are one kind of risks while with larger organizations open-sourcing there are other kinds of risks. If they are competitors in some way that's another challenge. If there is no natural alignment of use-cases functionally or non-functionally, that's another issue etc.

With recent changes in Redis, all these things have become less clear and straightforward.