If you use the same current branch software as your production environment, you need an explicit license. Check with your account team to determine if your specific license agreement covers multiple instances in multiple environments.
Some developer programs like MSDN offer products like Configuration Manager for development and test, but not production use.
For a temporary environment, you can use the evaluation version for 180 days.
For a lab environment, you can use the technical preview branch. Technical preview has the same functionality as current branch, but has some limitations in terms of scale and supported platforms.