general queston for dummy users of oscommerce

This message was sent from: GNU General Public License
http://forums.oscommerce.com/viewtopic.php?p=202288#202288
----------------------------------------------------------------

sorry i'm not a digital dummy, but:
 :?:  :?: 
i have three possible clients (i'm a web-engineer) who would like to use the famous osCommerce Shopsystem. MY BIG QUESTION:

is there any cost-position for useing the osCommerce System?
without changing the System of OC?
May be there is a Licence or some other costs if have to pay to OS.

Please help me,
i'm a newbie by osCommerce - and I just wanna do nothing wrong...

sorry for this bad english - but i'm trying.

thanks for being human
cschmitt :?:  :?:  :?: