Sometimes even after licensing Foxit PDF SDK ActiveX you can still get a watermark on your PDF files. The most common problems causing that are described below:
License is not applied correctly. Please call UnlockActiveX after the ActiveX component initialized. Please also check if there is spacing in the unlock code that shouldn’t be there.
Not using the licensed ActiveX OCX that was provided with the key. If you mix and match the evaluation OCX and the licensed OCX, you will get an evaluation watermark even if you called unlock correctly.
The watermark was already on the PDF. Open the PDF with another PDF Reader to check if the watermark is already on the PDF. The PDF may have been modified by the evaluation version of the Active X and the watermark maybe placed on the PDF itself.