A user with an active Visual Studio Enterprise subscription can be assigned the "VS Enterprise" or "Basic + Test Plans" access level in an on-premises Azure DevOps Server using local Active Directory accounts without incurring any additional licensing fees or purchase requirements. A valid Visual Studio Enterprise Subscription includes an Azure DevOps Server User Client Access License, which is often called a CAL. This CAL covers your access rights for your on-premises deployments.
The "VS Enterprise" access level in Azure DevOps Server maps directly to the entitlements of your active subscription. This subscription already includes full features and Test Plans functionality. Using local Active Directory accounts does not invalidate your subscription rights. On-premises Azure DevOps Server relies on administrative assignment and CAL coverage. It does not require mandatory cloud identity linking for license compliance.
Because it is an on-premises deployment authenticated via local AD, Azure DevOps Server does not require the local AD identity to be tied to a Microsoft Entra ID or a public Microsoft Account to honor the subscription-based CAL coverage. Your organization should ensure that the number of active Visual Studio Enterprise subscriptions matches or exceeds the number of users assigned to these higher-tier access levels on the server. Your team remains responsible for tracking that every local AD user given this access level actually holds a matching, active subscription in real life.
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hth
Marcin