The current version of the "Lite" software. If you buy almost any entry-level Steinberg or Focusrite product, you get this for free.
Cubase 5 Lite: Everything You Need to Know About the Legacy DAW cubase 5 lite free download install
Download the latest version of the eLicenser Control Center from Steinberg’s website. Even for the Lite version, the software needs this to manage your activation code. The current version of the "Lite" software
While Cubase 5 Lite was great in 2010, the "Lite" DAWs of today are much more powerful and actually optimized for modern computers. If you can't find your Cubase 5 key, try these: cubase 5 lite free download install