Earlier quoted context omitted.
With OS X there's no license key you need to enter, they have a poem instead asking you not to steal it. That's a nice thing, rather than assuming you're going to steal it they have a poem to jokingly ask you otherwise.
Sure, no license key, except for the key used to decrypt protected binaries only on authorized hardware. There is a license "key", it's the whole computer.
As far as I know, as long as all the hardware is stuff OSX has drivers for (and you generate a DSDT to describe that hardware) then you don't need any special "authorization." You just put in the OSX installer USB/DVD and it works.