I believe your issue is with the app, not with the device. From the app's page, I see some users complaining about ads appearing in a paid app:
Your complaint should be directed towards the app maker:
Please contact the developer directly if you would like to report a problem:
Spam or pop-ups on these devices are almost always due to the app developer. Look for the contact information for the developer and direct all inquiries to them.
You can turn off ads in WWF with an in-app purchase from their store if you're running the free version from the Google Play Store, but the B&N apps are "supposed" to be ad-free. Am I understanding your correctly that you're seeing ads in the version from B&N that you paid $2.99 for? I don't have a stock NC to test on, but can you access the Zynga store in-app?