I have this library! Is any examples how to get text or images from pdf?
Take a look at iTextSharp. It is a C# port of iText. It is licensed under the AGPL v3. It should be able to pull out the text for you.
Yes it is definitely important to understand the terms of the AGPLv3. It often requires publishing your source code, among other things, if you wish to use the iText stuff freely.
iTextSharp (versions after 5.0) may be not that free as one may think. See itextpdf.com/terms-of-use for more info.