Hi Lucy. Totally! You can feel free to do this; the easiest way would be to activate it on the test server / plug in the license key / then deactivate the license key for that site on tri.be and re-add it to the new site upon going live.
Realistically, you don’t even need to enter the license code on your dev site. No functionality stops working without a license code; you just cannot get plugin updates or access the support forums without one. But in most cases there’s no need to enter the license on your dev site unless you want to.
Hope this helps! Let me know if you have any other questions.