I am developing an application with C# that works with PDFs among other things. To render PDFs on screen I want to use the ActiveX Control from Adobe Acrobat Reader. I already found some tutorials on web about how to do this. I want to sell this app, and my clients must have Acrobat Reader installed on their computers for this functionality to be enabled. The installation kit will not include anything from Acrobat Reader (except for interop assemblies).
My question is: to sell this app do I have to pay some fee to Adobe because I'm using Acrobat Reader's functionality?