When getting a license, you first get to see a preview of the license agreement.
Just take a look after clicking the "license" button on the registered song you want to license. There's a link to the preview written in red on the same page and you'll get a description of what you can and cannot do. You can read it as thoroughly as you want, and get the license when you are ready.
Your preview will be updated automatically when you enter the required information for your license to be active. Once you've activated your license (which you need to do asap before releasing your new song), you'll get a complete and valid license and no longer previews.