with ImageEnView1 do
  begin
    IO.LoadFromFile('C:\pic\bg.png'); //640x640
    LayersAdd;
    IO.LoadFromFile('C:\pic\prod.jpg'); //1600x1200
    CurrentLayer.Cropped := True;
    IO.SaveToFileJpeg('C:\test.jpg'); //1600x1200
  end;

with ImageEnView1 do
begin
    IO.LoadFromFile('C:\pic\bg.png');
    LayersAdd;
    IO.LoadFromFile('C:\pic\prod.jpg');
    CurrentLayer.Cropped := True;
    LayersMergeAll();   // <<<<<<
    IO.SaveToFileJpeg('C:\test.jpg'); 
end;

  with ImageEnView1 do
  begin
    IO.LoadFromFile('C:\pic\bg.png'); //640x640
    LayersAdd;
    IO.LoadFromFile('C:\pic\prod.jpg'); //1600x1200
    CurrentLayer.Cropped := True;
  end;

  // of course you need also "var bmp:TIEBitmap"
  bmp := TIEBitmap.Create(ImageEnView1.Layers[0].Width, ImageEnView1.Layers[0].Height);
  try
    ImageEnView1.LayersDrawTo(bmp);
    bmp.Write('C:\test.jpg');
  finally
    bmp.Free();
  end;