The Agent2 module is a separate software package (a module in Go terminology), and package management utilities consider the directory containing a go.mod file to be the root of the module.

Subsequently, management utilities expect to find a license file at the root of the module to determine its licensing.

The Agent implementation in Go is licensed under the same license as the Server, Proxy, Agent and the rest of the Zabbix source code (sans the plugin-support and plugin packages for Agent2). A copy of this license should be added to the Go module.