I think there is a bug in the latest version of PDFelement that prevents customers who have purchased it, to activate it. Although I have pointed this out to customer services several times, nobody seems interested in fixing this bug and Marlin Gardner seems to be having the same problem which for me has been going on for at least 2 months. I even purchased a second copy but that doesn't work either. And I have downloaded the app again and it still doesn't work. I have attached a screenshot of the bit that doesn't work ("Purchase to remove watermark"). The button on the right "refresh" does not respond when you click it, the button depresses but nothing happens. PDFelements seems to potentially be a good app compared with others that I have used like Soda PDF, but the support staff are spoiling it by poor service and lack of attention to fixing problems.