Open Source implementation.. Is free?Or do we have a moral obligation towards it?"

An open-source implementation is essential for several reasons. First, it allows collaborative software development by a community of developers. This often leads to better quality software, as more people can review the code and make improvements. In addition, open-source software is often more adaptable, as users are free to modify and adapt it to their needs. Of course, it would be possible to start a project from some equivalent open-source software and then modify the license to commercial closed-source software; obviously, the open-source software chosen by the license should allow this. 

However, from an ethical point of view, we would have a moral obligation to offer back in some way the work taken from the open-source software; it is an obligation that we should all respect.

In terms of contributing back to the open source community, it is considered an ethical obligation for those who use open source software to contribute back to the community in some way. This can take many forms, such as reporting bugs, submitting patches, or providing documentation. By doing so, users help ensure that the software remains up-to-date and functional for everyone who uses it. Moreover, contributing back to the community is a way to show appreciation for the hard work of the developers who created the software, and to help ensure that the open source ecosystem remains healthy and sustainable.