There are dot net libraries in the download zip file.
There is another .NET library here, and a tutorial on how to use it.
This has a BSD license which means you are free to use it in your commercial product without a problem. Open Flash Chart is GPL
which also means you can use it in a commercial product (see the download page for more details.)
Try using them all to see which fits your project the best :-)
Will Schreiner, has a .NET library and tutorial (compatable with 1.9.6) here:
Here is a cool little .NET tutorial (VB.NET) :
open flash chart, dot net, it isn't in English, but the
code is simple to read and you can cut-and-paste it fine :-)