Why Do I Have the Watermarks Added in My PDF File on Mac? How Do I Remove Them?
The watermark is simply a limitation of the free trial version. When you use the trial version, you can click "File" > "Save As" button on the top menu to save your edited PDF file, in this way the watermark will be added in the new copy file, it won't affect your original PDF. After purchasing the product, please open the watermarked PDF in the registered full version, the watermarks will be removed automatically, you just need to save your PDF again. You can refer to the link below to know more instructions:
https://pdf.wondershare.com/pdfelement-mac/user-guide.html#register