Nine Unique Colors (perhaps more): I recall people complaining in many places about the "only 5 unique colors per profile" barrier for the keyboard (also, from Step 15 in section "To create your own custom color profile" in tmaeller's above guide/manual),
"15. Repeat as needed until you're satisfied. Remember that you only have five layers, which means that you can only configure up to five colors." ...and so far I haven't seen anything contradicting that limitation...until now.
...using this guide (another thanks to tmaeller), with judicious application of the CTRL key and the "Opacity" setting to create mixes of colors, I've so far been able to produce 9 unique colors in a single Profile. I think one could create at least 2 (note1) more unique colors for a total of 11 unique colors per profile, or there may be even more possibilities (note2).
So far I've been using only "Lighting effect = Static On" so I have no idea if that could affect color variability. Given the software...who knows? (note3)
To provide clarity...one
can DISPLAY more than 5 colors using the methods I describe, however as far as I can tell, the total colors displayed in a given profile are still limited, but now include more colors created by blending of the initial color and opacity and any overlapping one chose when setting up each layer in that profile...and as one manipulates and blends them using the CTRL key and overlapping layers.
My test profile produces
Red, Blue, Green, Yellow, Orange, Purple, Soft Pink, Sky Blue, and OFF(="Black")
The colors are distributed non-contiguously across the keycaps, not just in monolithic single color groups.
Note that I am defining LED=OFF as the color "Black".
Layer 1 = Primary Red color disc; 80%
Layer 2 = Primary Green color disc; 35%
Layer 3 = Primary Blue color disc; 50%
Layer 4 = Sky Blue color disc; 100%
Layer 5 = Yellow color disc; 100%
(note1) I was able to get 7 unique colors (including Black) in 3 layers, so I'm speculating we may be able to create 2 unique colors for each of the 5 layers in a profile, plus the OFF (or Black) "color" for the possible total of 11 colors.
(note2) We may be able to obtain additional colors per profile by using the CTRL key in other ways or changing "Layer" sequencing. I'm sure I haven't found all possible CTRL/Layer/Opacity/LightingEffect interactions.
(note3) I am using version 1.0.8.0 and so far haven't found a compelling reason to upgrade it.