MasterPDFEditor4 (PDF editor)

Master PDF Editor allows you to create, edit, preview, encrypt, sign
and print XPS and interactive PDF documents.

Its powerful editing features allow you to convert between PDF and
XPS formats; add interactive controls such as buttons, text fields,
check boxes, and event handlers to your documents; split and merge
PDF files.

The Linux-based version is free for non-commercial use.

This is version 4, which still saves without a watermark from the
trial version.

The first time you run MasterPDFEditor4, it will tell you a new
version is available and offer to download it for you. You should
answer No to this prompt; if you are looking for the latest version of
the program, look for the "MasterPDFEditor" SlackBuild, instead.