There are two licensing models for running enterprise Metabase.

With the standard model, which is what we are licensed for now, you configure a license key via UI and Metabase makes an outbound web request (to AWS) periodically to validate the key. The number of user accounts is also reported as a verification of the self-reported user count, since licensing is based on the number of active users. The same license key can be used for additional instances, but pricing is based on user+instance so we would need to report the UUID from each test instance to the licensing team to make sure it is excluded.

There is also an airgapped model, with different pricing, where you're provided a jar to install that handles licensing and time-validation. In this model, each upgrade requires a new jar.

https://www.metabase.com/docs/latest/paid-features/activating-the-enterprise-edition

We are running the open source version essentially airgapped, which blocks us from switching to enterprise.

We have the option of routing the request through a proxy, but it requires significant configuration and testing. We can do that work in a sandbox if have a test key (preferable) or are sure we don't invalidate the production key by using it on more than one instance.