Way to allow to developers to implement an SDK in a test environment but not production with a hard stop

I'm creating an SDK and looking for a recommendation on how to let a developer implement and test the SDK with a tag and token but prevent them from deploying it in a production environment without switching out the API key or tag and token. I'm trying to prevent them from saying its in test but actually deploying it in production because my pricing is based on number of times the SDK is invoked.