You can use up to 2 development/testing licenses. The first development license is free of charge. The additional dev licenses are provided at 50% discount of the original price.
The software must be installed in a subdomain of your main domain and cannot be used for production. For example, if your domain is example.com, you can use it at test.example.com. You need to let us know the subdomain where the software will be installed in advance.