procedure TForm1.AddTitleKeywordsAndCategoryToAnExcelFile(Sender: TObject);
var
   ExcelFileName: String;
   ExcelApplication, ExcelWorkbook, WorkbookProperties: Variant;
begin
     //be sure ComObj and Variants units are included in the "uses" clause

     ExcelFileName := 'C:\PhysiologyWeb\delphi_code_examples\excel_file.xlsx'; //replace file name with the name of your file

     ExcelApplication := Null;
     ExcelWorkbook := Null;
     WorkbookProperties := Null;

     try
        //create Excel OLE
        ExcelApplication := CreateOleObject('Excel.Application');
     except
           ExcelApplication := Null;
           //add error/exception handling code as desired
     end;

     If VarIsNull(ExcelApplication) = False then
        begin
             try
                ExcelApplication.Visible := True; //set to False if you do not want to see the activity in the background
                ExcelApplication.DisplayAlerts := False; //ensures message dialogs do not interrupt the flow of your automation process. May be helpful to set to True during testing and debugging.

                //Open Excel Workbook
                try
                   ExcelWorkbook := ExcelApplication.Workbooks.Open(ExcelFileName);
                except
                      ExcelWorkbook := Null;
                      //add error/exception handling code as desired
                end;

                If VarIsNull(ExcelWorkbook) = False then
                   begin
                        //get BuiltinDocumentProperties
                        try
                           WorkbookProperties := ExcelWorkbook.BuiltinDocumentProperties;
                        except
                              WorkbookProperties := Null;
                              //add error/exception handling code as desired
                        end;

                        If VarIsNull(WorkbookProperties) = False then
                           begin
                                WorkbookProperties.Item['Title'].Value := 'Delphi Code Examples';
                                WorkbookProperties.Item['Keywords'].Value := 'Delphi, Object Pascal, Code'; //this is also referred to as the "tag" property
                                WorkbookProperties.Item['Category'].Value := 'Delphi Programming';
                                WorkbookProperties.Item['Company'].Value := 'PhysiologyWeb';

                                //use WorkbookProperties.Count to parse through all BuiltinDocumentProperties (Name/Value) and read/write as desired
                                //for a complete list of BuiltinDocumentProperties, see reference below
                                //https://docs.microsoft.com/en-us/dotnet/api/microsoft.office.tools.excel.workbook.builtindocumentproperties?view=vsto-2017

                                ExcelWorkbook.Save;
                                //or
                                //ExcelApplication.WorkBooks[1].Save;
                           end;
                   end;
             finally
                    ExcelApplication.Workbooks.Close;
                    ExcelApplication.DisplayAlerts := True;
                    ExcelApplication.Quit;

                    WorkbookProperties := Unassigned;
                    ExcelWorkbook := Unassigned;
                    ExcelApplication := Unassigned;
             end;
        end;
end;