I apologize if this question is not suited for the website. I m ready to delete it if that's the case. I would like to use Mathematica for my PhD research. I will have a laptop that's limited in capabilities and so it can't run the newest versions of Mathematica. Can I (in Dec 2020) purchase one of the older versions of Mathematica from Wolfram's site to be installed on my laptop ? It would be great if I can purchase Mathematica 8 now for example. What is the earliest version of mathematica which I can purchase? My last question is what are the disadvantages of purchasing the older versions of Mathematica other than missing the opportunity to use the new features in the latest versions of Mathematica.