You are configuring Google Chat for your organization.

Configure Google Vault to retain all Chat messages, and exclude organizational units (OUs) with users who want to turn Chat history off.

Set the space history setting to OFF and chat history to ON.

Set the top-level default conversation history setting to ON and allow users to change their history setting.

Set the top-level default conversation history settings to OFF and allow users in each organizational unit (OU) to change their history setting.