Developers of open-source software tools/packages under a dual license ("free" as well as commercial) , where/how do you track who is using your "free" software?
You offer some part of the product behind an always online portion that requires account creation. The premium users will pay for access to it.<p>Dual licensing the code itself requires an honor system which is fine, but has an upper limit on growth if that's what you're optimizing for.