Indeed, there is a trial for Nuendo 5.5 and a regular Nuendo 5 license on the USB-eLicenser.
However, I assume that the program installation of Nuendo 5.5 went fine as you can use it as the trial version.
I have placed a Nuendo 5.5 activation code into your MySteinberg account. If you log in, you can see a new code is waiting for you.