Mut'ah

This is not a nikaah, rather it is the muta'h that is practised by the Shias. Muta'h is where a man and woman enter into a temporary nikaah e.g. they state that they are marrying for a few hours or a few days in lieu of wealth in order to satisfy their sexual desires and thereafter separate. This is not a nikaah, instead it is zina. This type of arrangement is totally haraam in Islam. As long as they remain together, they both will be living in zina.

And Allah Ta'ala (الله تعالى) knows best.