If you have authorized multiple eReaders and computers with Adobe Digital Editions using your Adobe ID, you may get an error message saying "Too Many Activations" when you try to authorize again. This is because Adobe puts a limit on the number of times you can use an Adobe ID to authorize a computer or eReader. You can, however, request additional authorizations. 

Here's how to request more authorizations:

• Go to http://www.adobe.com/go/supportportal
• Sign in with your Adobe ID and password.
• Under "Get Support," in the "Technical Support" tab:
  • Under "Choose issue type" select "Using a product or service."
  • Under "Choose product," first select "Additional Products," then select "Adobe Digital Editions."
• Fill in the online form, describing the problem and asking for additional authorizations.  You should get an e-mail from Adobe in a couple of days letting you know that they've reset your authorizations. You can then re-authorize your eReader in Adobe Digital Editions.