Where should I call the PDFNet initialize?

This is a very common question when using PDFNet for the first time. PDFNet initialize must be called before any other methods call with PDFNet.

pdftron.PDFNet.Initialize("Insert commercial license key here after purchase");

The best location would be your application start-up function (such as main(), OnAppStart(), DLLMain(), etc. - depending on our application type and development platform).