Once you've purchased a design, getting the download from the editor will still give you a free basic quality download as usual. Instead, you need to go to your 'Order History' for the purchased design. Click the download button under your order to go to the download page. From there, you can download the purchased design. The download link is also sent to your email.
If you've followed the above procedure, and your high resolution download still contains a watermark, it's possible one of the images is a premium stock image downloaded for free. In that case you will have to replace the image with another image.
If this problem occurs with a template, report the issue via our contact form, so we may find a replacement of this image.