Enhance Speech Premium won't let me export as wave (the free version did!)

Before signing up for Enhance Speech Premium I was able to export as WAV using the free version, but having signed up to Premium, it only lets me export as 64kbps mp3. I am trying to enhance some old poor quality audiobooks that were recorded from tape in very poor quality. The enhanced speech result is fantastic, but I need them in high quality wav, so can later convert them to m4bs. Why is this not possible? I am considering cancelling my trial if I can't do this.