Quote - Does this mean the stuff bought in market places can not be used? Just a little confused.

No, far from it.  Most of the products you buy here and elsewhere will permit full commercial use, some will not.  The donors of freebies often don't permit commercial useage, but many do.  The advice is to read the licence when you install, and if you ever find yourself in the position of your work being potentially used for commercial purposes, check and re-check the licences of the content you used to make your work, including Photoshop brushes! In my case I had some old models that I couldn't find the licences for to check, so decided not to take the risk.

Some licences which permit commercial useage also have other restrictions though - I know of one VERY popular vendor who does not allow 3D real-world models to be made from their products, for example.

Check, check and check again. 

My self-build system - Vista 64 on a Kingston 240GB SSD, Asus P5Q Pro MB, Quad 6600 CPU, 8 Gb Geil Black Dragon Ram, CoolerMaster HAF932 full tower chassis, EVGA Geforce GTX 750Ti Superclocked 2 Gb, Coolermaster V8 CPU aircooler, Enermax 600W Modular PSU, 240Gb SSD, 2Tb HDD storage, 28" LCD monitor, and more red LEDs than a grown man really needs.....I built it in 2008 and can't afford a new one, yet.....!

My Software - Poser Pro 2012, Photoshop, Bryce 6 and Borderlands......"Catch a  r--i---d-----e-----!"