Docotic.Pdf library (I work for the company) may be used to accomplish the task.
Here is sample code:
using (PdfDocument document = new PdfDocument("file.pdf"))
{
string author = document.Info.Author;
string subject = document.Info.Subject;
string title = document.Info.Title;
string keywords = document.Info.Keywords;
// ...
}
Beyond that the library can do many other things. There are samples for common tasks available online.
