Yes, you can use your license on test or staging sites – they do not count against the license limit.

TLDs that are considered as dev or staging:

• *.dev
• *.dev.cc (DesktopServer)
• *.test
• *.local
• *.staging
• *.example
• *.invalid
• *.myftpupload.com (GoDaddy)
• *.cloudwaysapps.com (Cloudways)
• *.wpsandbox.pro (WPSandbox)
• *.ngrok.io (tunneling)

You can check out more details here:

freemius.com/help/documentation/selling-with-freemius/license-utilization/