I just purchased a license key but that is for the production environment. How do I install and setup Expression Engine in my development server?
As long as you have a valid license, there is no issue with duplication. Just use the license for your development environment, and push it to the production environment. If you already have production set up, just clone the repo to your development environment.
EllisLab is not made up of monsters; many people run EE applications with a duplicated development/production set up. They know that. If you start using the license for different production environments, then you are violating your license in a way that can get you in trouble.
Concerned? You just gave them a bunch of money. Shoot them an email if you are really worried about it. I have a few things in the wild with a repository setup between development and production. To really avoid any possible issues, host your development install inside your production environment.
https://www.example.com --> production install
https://www.example.com/dev --> development install
Then just set up your
.gitignore file to ignore itself, and customize it for your dev and your production setup. It will take some time to setup right, but once it is right, you are golden.