Seta Bridge Plugins
These plugins act as "bridges" between either WooCommerce or Easy Digital Downloads (EDD) and the SetaPDF-Stamper library, which is not licensed for distribution in GPL plugins. SetaPDF-Stamper needs to be purchased separately and installed with the Little Package Stamper plugins for them to stamp.
If you want to watermark and/or encrypt and password your PDFs -- and preserve their internal links and metadata -- these plugins will work for you. Otherwise, if your PDF does not have hyperlinks or other advanced features, WaterWoo or EDDiMark will work fine for you.
These plugins are more advanced to setup and suited for developers and folks very serious about their PDFs
Download Monitor Stamper
Connect Download Monitor to the SetaPDF-Stamper library by Setasign. Stamp & protect your intellectual property. Best for PDFs with internal links and fillable forms.
Use the powerful SetaPDF-Stamper PDF stamping library by Setasign for PDF watermarking Easy Digital Download deliverables. Best for PDFs with internal links.