Once you’re happy with the watermarked preview PDF, to generate a PDF with no watermark you’ll need to purchase a license to PMB Pro.
For that, from anywhere in the WordPress admin dashboard, under “Print My Blog” click either “Upgrade” or “Pricing”. Select the plan that works for you and make the purchase (you can do it all from within your WordPress website via a payment system called Freemius).
After you’ve purchased a license, the Generate Project step will say how many more Paid PDF downloads you have available.
Just download the watermarked Preview PDF, double-check it’s good, and then click to download the Paid PDF.
The Paid PDF is identical to the watermarked Preview PDF, just without the watermarks.