Abstract: A virtualization system supports secure, controlled execution of application programs within virtual machines. The virtual machine encapsulates a virtual hardware platform and guest operating system executable with respect to the virtual hardware platform to provide a program execution space within the virtual machine. An application program, requiring license control data to enable execution of the application program, is provided within the program execution space for execution within the virtual machine. A data store providing storage of encrypted policy control information and the license control data is provided external to the virtual machine. The data store is accessed through a virtualization system including a policy controller that is selectively responsive to a request received from the virtual machine to retrieve the license control data dependent on an evaluation of the encrypted policy control information.