Dual Use Rights allow CRM Online User Subscription Licenses (USL's) to access on-premises CRM servers - eg. CRM Online Pro includes Pro CAL rights, etc.
All server licenses are still required, as are all other Client Access Licenses (CAL’s) e.g. Windows CAL. Dual use rights are provided by the CRM 2015 Server license
Use Dual Use Rights to:
- Add new on-prem users when planning a cloud migration
- Supplement a CRM Online Deployment with a CRM Server for eg. Dev/Test purposes
- Access a licensed CRM Server instance running in Azure