The 'Juicebox' branding is appearing in the bottom right of the gallery. Isn't that removed when upgraded to 'Pro'?
Yes. The Juicebox badge/link at the bottom right corner of the gallery is present only in Juicebox-Lite galleries and is not present in Juicebox-Pro galleries.
Try clearing your browser's cache before reloading the gallery to ensure that your browser is not hanging onto and using older versions of your gallery files.
If you still see the Juicebox badge/link after clearing your browser's cache, then your gallery's 'jbcore' folder has not successfully been replaced with the Pro 'jbcore' folder.
If you are in any doubt as to whether or not your gallery's 'jbcore' folder is being overwritten, try deleting it from your web server first before uploading the Pro 'jbcore' folder in its place.