A serial number for Prism 8 will not work for Prism 9 or 10. Ensure the installer version matches your license key.
To activate GraphPad Prism 8, follow these steps: Graphpad Prism 8 Serial Number And Activation Code
If you need GraphPad Prism 8 (or the current version) for your research, there are several legal and often affordable ways to obtain a serial number: A serial number for Prism 8 will not work for Prism 9 or 10