All editions of Windows Vista (excluding Enterprise) are stored on the same retail and OEM optical media—a license key for the edition purchased determines which edition is eligible for installation. When first announced, Anytime Upgrade enabled users to purchase a digital license from an online merchant to upgrade their edition of Windows Vista. Once a license had been purchased, a user's product license, billing and other information would be stored within a user's digital locker at the Windows Marketplace digital distribution platform; this would allow a user to retain this information at an off-site location for reference purposes and to reinstall the operating system, if necessary. A user could then initiate an upgrade to the edition for which the license was purchased either through components stored on the hard drive by the OEM of the personal computer, through an Anytime Upgrade DVD supplied by the OEM, or through retail installation media compatible with Anytime Upgrade. If none of these options were available, Anytime Upgrade provided an option for a user to purchase a DVD online and have it delivered by mail.