Which Stack Exchange site to use for this question
None. Shopping questions don't fit the Q&A standards of Stack Exchange.
I will imply this is the question you're talking about.
It was closed as not constructive as explained under the question :
Which is good news for you since it wasn't closed as off topic. You were in the right place but didn't ask the right question or didn't ask the right way. You can't simply ask for such a solution on Stack Overflow. But, on your way of doing this :
So we need to set up a licensing server to check number of users using the app.
If you encounter a specific problem, you can always come here, show what you've tried and what failed, provide some code and get the desired support.
You should refer to the FAQ to know how to ask a good question that fits the site's standards.