Caddy is still Apache 2.0 licensed. You can use it for free for commercial purposes. You just can't use the build server at caddyserver.com to download a precompiled Caddy with plugins. Instead, you can download the source, compile it with plugins yourself, then distribute your own binary amongst all your hosts.
Personally for me Caddy is (was) good because of how easy it is to set it up.
The most popular Docker image for Caddy, for example, should soon (if it's not already) be compiled from source, rather than from the build server. That means it will remain free to use, and I personally don't have to make a single change.
If this has impacted you negatively to the point where setting up nginx is an easier option, well - that's the beauty of choice!