I have used Aspose.Slides Dll in my project. After converting PPT file to PDF .In PDF file I am getting "Evaluation only.
Created with Aspose.Slides for .NET 126.96.36.199.
Copyright 2004-2011 Aspose Pty Ltd."
I like to share that you are getting the watermark due to missing license in your application. You need to call Aspose.Slides license for your application. Please visit this documentation link for your kind reference. Please also visit this link for your kind reference.