Adobe only sells Lightroom 6 or Lightroom CC. If you want to upgrade to Lightroom 5 then you will have to find it for sale as an upgrade from a seller like Amazon or B&H Photo, etc. I think you will find it very difficult to find Lightroom 4 anywhere. If you're going to upgrade my opinion is that you might as well upgrade to the latest version. The cost is the same. If you haven't mastered Lightroom 3 then you might want to take the time to watch some introductory videos. The link I am providing is for Lightroom 5, but everything that is discussed will apply to other versions as well.