Hi are you developing in BC On-Premise and then don't have a development license?
If you are using the On-Premise version, you can copy a new database for development, just like the Sandbox in SaaS, and upload it to the production environment after the extension is completed.
Sandbox uses development license, production environment uses customer license, and may need to temporarily update the license when releasing the extension.
Hope this helps as well.
Thanks.
ZHU
