snsa, Since you authorized your computer without a Vendor ID(anonymous), you will not be able to transfer eBooks to your Nook. However there is a way to de-authorize ADE and re-authorize ADE using a new adobe ID.
- Launch ADE.
- Press Control+Shift+D (Windows) or Command+Shift+D (Mac)
- You will get an option to Deauthorize or Erase Authorization(depending on your ADE version), click it and you are done.
- Go To Help-> Authorize Computer.
- Enter your credentials and authorize ADE.
Once authorized, try to transfer eBooks to your Nook and check if that helps.
Let me know in case you get any issues while following the above suggestions or need any further help.
Cheers!
~ Arpit