I have full version and with it you can add a new material just clicking on “+” icon that you find in the top/right area of the configuration panel (ofcourse inside inspector).
Any way; I found that there is No + - in the trial version
Moreover when the material assigned to an object there are water marks.
By the way I am using Unity 3.5.5f3
To make several materials, I tried a simple trick…
It is to copy the material (sbsar) outside Unity,inside Explorer, and return back to Unity to use another Diffuse texture map in the copied one.
Note:
I found out that both releases (Trial Full) with file size 1.4 MB
May be <> can help us and tell how much rich is the full version more than the free one, since he said he had the Full one
I can guess he had tried the Trial free one before paying 75$