First off, the software should install without activating any license. Only when trying to run it, the check for the licene will be done. So does your laptop comply with the minimum requirements for Wavelab LE?
Then, you won’t need a USB-key for a Wavelab LE license, but you probably will have to install the E-Licenser Control software: http://www.steinberg.net/en/company/technologies/elicenser.html. In this software, you’ll have to enter the license activation code that came with your WL LE and you should be ready to go.