Hi,
This is not an activation limit issue as I checked and they are still left.
I would request you to follow the below steps to de-authorize and re-authorize ADE.
For Windows OS-
Close ADE
Open registry editor and navigate to 'HKEY_CURRENT_USER\Software\Adobe\Adept '
Right click on Adept and choose Delete.
Once its deleted then close Registry Editor and launch ADE and reauthorize your computer with new ID.
For Mac OS-
Close ADE
Navigate to /Users/Library/Application Support/Adobe/Digital Editions
Drag the activation.dat file to the trash.
Try to authorize your computer by opening ADE, clicking on Help menu, choose authorize computer, enter your email address and password and clicking on Authorize.
Regards,
Mayank
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