When a user is not logged in, this is done implicitly (no click to accept is required). Out of respect for our users and to be fully transparent, we surface a banner when the user is not logged in to bring this implicity agreement to their attention.
When a user is logged in, the agreement must be explicity. During signup the user is prompted to agree to the terms and must do so in order to continue using the application. If the documents have been updated since the user last agreed, they will be notified of this change and once again asked to agree to the updated terms/policy.