aqprox appEB02G Mode D'emploi page 38

Notes in using ADE
9
Each ADE ID supports only 6 devices, this includes the master device
(the reader) and the slave device (TF card).
When the reader is restored to default settings, ALL DRM activation
record and data (including DRM books purchased) will be erased from
the reader. You are required to authorize the device with your ADE ID
again.
When the number of authorized device has exceeded the allowable
amount, you will come across the following error message:
E_ACT_TOO_MANY_ACTIVATIONS
To request for extension and reset of your ADE ID, go to
 [Submit a web
http://www.adobe.com/support/digitaleditions/
case]. You are required to key in your ADE ID info.