When u get a file from web or sale a product to ur custom,
u have to update it urself when a new version fond,how can I
liveupdate it like Norton AntiVirus, Now, u can get some info
from here.
                            
3 k u

first of all ,u need create a HInternet when it is created as following

constructor TULiveUpdate.Create(AOwner: TComponent);
var
  FINet: HInternet;
  // U need add WinINet to uses first
begin
  inherited;
  FINet := InternetOpen('WinINet1', 0, nil, nil, 0);
end;

then u need check if it is need update?

function TULiveUpdate.NeedUpdate(const FileName: string): Boolean;
var
  LFileS, SFileS: Integer;
  LFileT, SfileT: string;
begin
  // Link to ftp Server(u need declare FPath first)
  FftpHandle := InternetConnect(FINet, PChar(FPath), 0, '', '',
    Internet_Service_Ftp, 0, 255);
  if FftpHandle = nil then
    raise Exception.Create('Can''t link to ftp Server'+ FPath + '!');

  // Compare FileSize
  LFileS := GetFileSizeA(FileName);
  SFileS := GetFileSizeW(ExtractFileName(FileName));
  // Compare FileDate
  LFileT := GetFileDateTimeA(FileName);
  SFileT := GetFileDateTimeW(FileName);
  Result := (LFileS <> SFileS) or (LFileT <> SFileT);
end;

last , u can LiveUpdate now, If file is run , u need close it and down it, then open it again

function TULiveUpdate.LiveUpdate(const FileName: string): Boolean;
var
  FileIsRun: Boolean;
  hFile: THandle;
begin
  FileIsRun := FileIsInUse(FileName);
  // u need set TargetFile first
  if not FtpGetFile(FFTPHandle, PChar(FileName), PChar(TargetFile),
    False, File_Attribute_Normal, Ftp_Transfer_Type_Binary, 0) then
    RaiselastOSError;
  if FileIsRun then
  begin
    // If file is run, delete it and open a new process to open the Lasted file
    DeleteMe(FileName);  
    hFile := OpenProcess(1, False, FileProcessID);
    if SameText(FileName, ExtractFileName(ParamStr(0))) then
      ShellExecute(Application.Handle, '', PChar(FileName), nil, nil, 1);
    TerminateProcess(hFile, 0);
  end;
end;