Premium Assurance was available for certain Microsoft products, but it is no longer offered as a new option. Customers who had already purchased Premium Assurance will have their terms honored. However, specific details about which systems were included in the Premium Assurance program, apart from Windows Server 2008, are not provided in the context.
Regarding the support duration, it is mentioned that customers who purchased Premium Assurance were supposed to receive the originally planned updates, but the exact end dates for Premium Assurance support are not specified in the provided context.
For further details on the Extended Security Updates (ESU) program, which replaced Premium Assurance, you can refer to the relevant Microsoft documentation for more comprehensive information.