Mats3 and MatsSocket, as well as MatsBrokerMonitor, is currently licensed under the noncompete Polyform Perimeter License, with a few examples of what you are not allowed to do. All the source is available at Github.
Polyform Perimeter is a noncompete license, which basically means that you can do whatever you want with the code, except using it to compete with the product. Thus, as long as you aren’t making a Mats-like product, or are AWS, GCP or Azure, or any similar company providing services to the public, typically for a fee, you should be in the clear. If you want to provide Mats or Mats-like features using Mats, we’ll need to have a chat.