I have a research-related project which currently has one developer (myself) and one sponsor (myself). It involves an open-source platform (AGPL3), and user submitted content which has its open-source licenses defined individually.
The project is 100% free, and I will be funding it till I find a sponsor to cover running costs (such as a public institution or foundation, i.e. not a for-profit company).
I also have other projects which are not free or open-source. The question is what are the ethics/legal pitfalls of linking these projects. How is this affected by contributions to the platform of the open-source project? How is it affected by sponsors? I can imagine that so long as I host the open-source project, there should be no issue in linking them, similarly to wordpress.org/wordpress.com.
My priorities here are not to maintain a link between the projects, but to make sure that I am not doing anything illegal in benefiting from my contribution (infrastructure rather than code in this case) to the free project by linking to the commercial project, AND to protect the free project from ever being commercialised.
An associated question is whether there are any other protections necessary for the free project, such as registering a trademark, which will prevent it being replaced by a for-profit project.