You can get and set PDF document metadata corresponding to a document's Info dictionary.  

You can also get and set the XMP metadata associated with a PDF or PostScript document. See the Metadata section for more information about the XMP metadata support in PDF and PostScript.

To manage PDF metadata you can use the GetInfo and SetInfo methods of ImGearPDFDocument. The following example illustrates the usage of these methods:

public void SetMetadata(ImGearPDFDocument igPDFDocument)
{
    // If empty, set the dictionary key "Author" to "Accusoft."
    if (igPDFDocument.GetInfo("Author") == "")
        igPDFDocument.SetInfo("Author", "Accusoft");
    return;
}

Public Sub SetMetadata(igPDFDocument As ImGearPDFDocument)
    ' If empty, set the dictionary key "Author" to "Accusoft."
    If igPDFDocument.GetInfo("Author") = "" Then
        igPDFDocument.SetInfo("Author", "Accusoft")
    End If
    Return
End Sub