License question for ESCROW deliverable

We have a customer who wants to get our source code to extend it by himself and 3rd party developers. How can this be handled with regards to our license. I would not like to give away my license key as part of source code, but surely they need to develop themselves. Do they need a license of their own?

Yes they’ll need their own developer license. Anyone who modifies a licensed project needs their own developer license.

Thanks for making this clear. I expexted this already, but it’s good to have it confirmed