When I change a new computer. I don’t know how to use Mathematica. I was a student from university and need a Mathematica program to finish my professor’s assignment. I bought it sometime before, but now I changed to a new computer and cannot find where I can download and use it without a new purchase.
Please read this: Wolfram Support Quick Answers: How do I move Wolfram software to a new computer?
If you have any questions, please contact Wolfram Customer Support:
Send them your Activation Key and tell them you want to move your copy of Mathematica to a new computer.