Is ambassador a licensed service? What should be preferred more - Envoy proxy or ambassador?
Ambassador Is open source software just like Envoy.
It's licensed under Apache-2.0.
It just so happens that this is the same license used by Envoy.
Ambassador does have a PRO version you can pay for to get a few more features.
Ambassador is a specialized control plane for Envoy Proxy.
So yes, they can do a lot of the same things, but with ambassador on a higher level of abstraction you'll get more value out of it more quickly IMHO. Even if you don't pay for their PRO version.
Envoy is like a lego brick, ambassador is like a spaceship made of several bricks. Envoy can be deployed on servers. Ambasador is built to be K8S native, and really easy to deploy. I don't know your use case specifically, but if I wanted an API gateway running in Kubernetes I would look at Ambassador over Envoy.