Create commercial license for a closed source library?

Background: I'm developing a domain specific web service development API. I am aiming for a closed shell / open core strategy in the long term. First releasing everything under the closed shell license. Which consists of a JVM jar and API documentation.

I'm looking for help drafting an appropriate commercial license. I can piece one together from templates, sort of. Does anyone have experience creating a license for a similar product? Any recommendations of legal resources for specific questions?

Thanks!