Ok after a litle searching I found a couple solutions.
You can Download the Lightwave 7.5c update and install it. It should install Lightwave and run in demo mode. --->
ftp://ftp.newtek.com/pub/Patches/Lig...Windows/lw75c/
You may have to download and install sentinal drivers for this method to work. --->
http://www.rainbow.com/downloads/sys...-32bitInst.zip
You can also contact Newtek and ask for a Lightwave Discovery CD which is the demo. I would try method one first.
http://newtek.com/support/cs/index.html
For restrictions I guess you can also not save scenes, its 400 points in a layer or object that you can save, and watermark. Not bad really though you can still learn and practice much with it.