I requested a reset of the copyright removal key (which Cubecart organised). My problem is that the register cubecart box in the admin section of the control panel now does not display. There is nowhere to enter the coyyright removal key. It is as though Cubecart thinks it is registered but will still not let me change the home page message etc.

Any help with this would be appreciated

Changing the homepage has nothing whatsoever to do with license keys. For instructions on how to change your homepage text please read the pinned posts.

If however you are saying that the copyrights are still in place then please submit a support ticket