The license server is used to handle the general check in and check out of licensing, which allows you to track how many users are concurrently accessing the software and helps you to comply with the Software Licensing Agreement.
Existing database/new database – You will be prompted to use an existing database or create a new one.
No sites/existing sites – If sites already exist on the server where the license server is being configured during license server creation, you have the opportunity to update the sites to use that license server.