Can I use my license on more than one computer or MT4?

Yes, you can. Your license is linked to your MetaTrader 4 account, not to a specific device, operating system, or IP.
You’re free to use the NNFX Algo Tester on multiple computer, as long as you're using the same MT4 account.

Need to switch accounts (e.g. from Demo to Live, or if your Demo expires)? No problem. You can transfer your license at any time by filling out a quick form and confirming your email. The process is fully automated:
https://nnfxalgotester.com/software/update-license/
Transfers are unlimited, but limited to one every 24 hours to prevent abuse.