We did have plans to implement NetWorx as a service, but eventually decided not to do it. Doing so would essentially mean a complete rewrite of the product since it's too tied to being a regular app.
Instead, we are currently working on a new product named NetGenius, which will run as a service. It will also have several advantages over NetWorx, including live usage display, speed limits for applications, and traffic prioritisation. It should be released in November.