TL;DR: Any license recommendation question that asks for an open license is on-topic.
Example 1:
I'm looking at open-sourcing project X, and I need a good open source license to do it under.
The requirements are X, Y, Z, and it needs to be A and B.
What is a good license for this and why?
This question:
- asks for an open source license
- asks for a recommendation
- asks for justification
In principle, answers to license recommendation questions should be backed up by reasoning and/or experience. This particular example is on-topic because it asks for an open license and gives enough details to successfully recommend one.
Example 2:
I want to open source a tool I'm developing, so I need a good open license so that people can use it. I'll be publishing on GitHub, so the license should preferably be in GitHub's list of open source licenses.
The license must forbid people I specify from using the tool, such as the military. It must also do D, E, and F things.
Can you recommend me a good license? I'd also appreciate reasoning behind your recommendation.
This question does the same as the last:
- asks for an open source license
- asks for a recommendation
- asks for justification
The difference here is that it sets out a requirement which precludes using an open license. However, this is still on-topic as it does ask for an open license. The answer should be along the lines of:
There is no open source license that matches your requirements, because X and Y. You could change your requirements or consider using a proprietary EULA (though we won't be able to recommend you one of the latter).
Example 3:
I've finished developing my project and I want to release it. However, because I spent so long on it, I want some specific restrictions on how people can use it:
- They have to tell me who they are and let me approve the request.
- They can't develop anything further from my code.
How could I license this?
This question is off-topic because it doesn't ask for an open license. The similarity to example 2 is that the requirements preclude an open license; however, this question doesn't actually want an open license in the first place - it just wants a license.