2003 Qashqai means import model from somewhere US or Japan. As in UAE its launched in 2007 -2008. So It must have this system inbuild for security reason as i know few countries have this security implemented as soon as you start the engine and all doors are closed they will enable central lock automatically in case driver forget to lock.
You have to change the central locking device system may be from Nissan or from outside who sells after market parts.