Here is the answer to this problem:, Error getting License. License Server Communication Problem: E

Your authorization file will need to be manually deleted.

You need to delete out a few registry keys to clear the activation for ADE. You must have administration authority.

On Windows it can be found here:
Open Windows Registry by using the command prompt and typing 'regedit' or by opening the start menu and searching for 'regedit'.

Search for the following folder:
HKEY_CURRENT_USER\Software\Adobe\Adept\Activation

The 'Activation' folder can be entirely deleted.

On Mac it can be found here:
In Finder, find the 'Go' option on the menu bar and click 'Go to folder' and type the following in:

~/Library/Application Support/Adobe/Digital Editions/

Delete the activation.dat file within the 'Digital Editions' folder.

Restart ADE and it should be deactivated at this point. You should be good to sign back in.