# License preview

The Flash application can send a license preview request, meaning that the
application can carry out a preview operation before asking the user to buy the
content in order to determine whether the user's machine actually meets all the
criteria required for playback. License preview refers to the client's ability
to preview the license (to see what rights the license allows) as opposed to
previewing the content (viewing a small portion of the content before deciding
to buy). Some of the parameters that are unique to each machine are: outputs
available and their protection status, the runtime/DRM version available, and
the DRM client security level. The license preview mode allows the runtime/DRM
client to test the license server business logic and provide information back to
the user so he can make an informed decision. Thus the client can see what a
valid license looks like but would not actually receive the key to decrypt the
content. Support for license preview is optional, and only necessary if you
implement a custom application that uses this functionality.
