Please download DoView now. Once you open it, select File > Register and put in the Registration Serial Number you have been emailed with your receipt. You may need to type it in rather than just cutting and pasting.
If your Mac says 'From an Unknown Developer' when installing
Right-click on the DoView application icon and select 'Open'. More information from Apple.
If you have a problem closing the File Selector Window when using DoView for Mac
When more than one instance of DoView is running, sometimes the File Selection Window can't be closed as normal. Close it by pushing ESC. As a precaution please save your work regularly.