3D FlipBook - How do I locate my account, and the registered install with the License key that I purcased?

You do not need to enter your license key, you need to use only files from pro version. You can always download the latest version using your purchase email.

Sadly, not true. I did locate the original purchase, and I was unable to download the plugin again. I ended up having to purchase a different plugin.

We resent your purchase email. Could you try once again?

We checked your purchase - it is WordPress plugin, not jQuery (you asked a question in wrong thread) so you need to enter your license key in the plugin settings after installation. Then it updates automatically.