Hello Hellene,
My wife and I are big believers in early education for children and at a very tender age the child is extremely receptive for language and music practice. Our daughter is only a year old, and she loves 'freestyling' with the piano keyboard. However, soon when finger control is a bit better, it might be a good time to gently introduce some real music practice and we have identified Soft Mozart as the method we want to try out. There seems to be so much research coming out unambiguously showing the benefits of children learning music instrument and additional languages. Music appears to be the gateway to unleash the full potential of the children's minds. According to research children learning and enjoying piano benefit in many other areas such as; creativity, math, brain power, confidence, memory etc.
Neither my wife and I are piano professionals, therefore we need to learn alongside our daughter and since we plan on using the software as our music teaching tool for a long time to come, the perpetual version makes the most sense.