In Eikon Data APIs the same app key can be used by multiple users. The validation of the app key only verifies if the app key exists. It does not check the relationship between user account and the app key. The purpose of the app key is to identify the app (client application or script, or Jupyter notebook etc.), not the user. We therefore recommend that the same app key is utilized for the same app irrespective of who runs the app. And separate apps keys are used for different apps irrespective of who runs them. E.g. if someone created a Jupyter notebook and shared it with 5 people, we recommend that the same app key is used in this notebook for all 6 users. But when the user creates a new notebook, we recommend creating a new app key.