AdiIRC

It only works if you have set a nickcolor for that nick or using random nickcolors, it does not work for extended (rgb colors), $rgbnickcolor must be used for them.

First of all, that is not how to use $nickcolor, $nickcolor returns the color number associated with the nick, nick colors must be enabled in Options -> Nick Colors, and there must be either a rule for the nick or random nick colors must be enabled.

If you only want the nick to be colored, you don't need to use $nickcolor, once nick colors are enabled the $pnick variable will already have the color.

A typical use case for $nickcolor is to allow coloring more than just the nick, something like <nickcolorchar>$nickcolor[$nick]<nickcolorchar>, in this case [nick] will be colored using the nick color, instead of just the nick.