Hi there,
The pdfjs express watermark will continue to show even with a license for development environment (i.e. localhost)
You definitely do not want to have two packages (Pro & Viewer) running at the same time as this will cause issues: Watermark still showing even with correct domain
Once you make the change, please try clearing the browser & server cache as listed in this post here: Pdfjs.express watermark despite licence key & correct domain
Best regards,
Kevin Kim