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Revoking Licenses
License issuers can revoke licenses that they have issued. Revoked licenses are removed from the consumer's computer, although the content remains.
Note This feature is not supported on devices.
This feature is useful to license issuers who want to develop a service that sets a limit on the number of computers on which consumers can play protected content. Using license revocation, consumers would be able to deactivate a computer in order to activate a different one.
For example, a consumer is allowed to play protected content from a particular service on three different computers. The consumer decides to purchase a new computer and give the old one to a friend. The user logs on to the service from the old computer and chooses to deactivate it. The service then revokes licenses for its content and removes this computer from the consumer's list of allowed computers. Then, the consumer visits the service from the new computer, the service activates this computer and issues new licenses to it for all the content that the consumer has purchased from the service. The old computer is given to the friend, who finds the music library left behind by the previous owner. If the friend tries to play the content, the license acquisition URL to the service is opened, and the friend can decide whether to purchase licenses for the content.
Note License issuers that use license revocation should not enable the AllowBackupRestore right. If consumers are allowed to back up their licenses, licenses can be restored after they are revoked.
Licenses are revoked according to various criteria, such as the key ID or a user ID, allowing the license issuer to revoke licenses in various situations. For example, using a key ID, the license issuer can revoke a license for a particular song. Using a user ID, the license issuer can revoke all licenses issued to a particular user (for example, on a shared computer).
This feature also allows consumers to return licenses. For example, a consumer purchases the wrong track, and so the license is deleted and a different one is issued. Or, the consumer purchases an expensive license that allows copying; the consumer decides to return that license and purchase a cheaper one that is more restrictive.
This section contains the following topics.
| Topic | Description |
| How License Revocation Works | Describes the interactions between the license issuer and the client when revoking licenses. |
| Implementing License Revocation | Explains how to revoke licenses. |
For additional information and sample code, see the Technical Articles on the Digital Rights Management page at the Microsoft Web site.
See Also