Is it true, that when I only want to use the "inthehand.net.personal.dll" in my commercial application, I do not need any license?

The InTheHand.Net.Personal.dll (32feet.NET) library is a shared-source project which is free for commercial or non-commercial use. You need to include a copy of the license document in your distribution and give details within your documentation / readme file so that users can access the original source project if they want to - http://32feet.codeplex.com if you distribute the library in source code form. If you distribute the InTheHand.Net.Personal.dll in compiled form only then you just need to ensure you use a license which is compatible with the MS-PL license which is used for this project see http://32feet.codeplex.com/license

 Peter