If you see the following dialogue window when licensing a new site then the current site is set up to use the SellerDeck trial hosting (Host Mode):
You can either register for some new trial space (http://trials.sellerdeck.co.uk/) and enter the username and password that is supplied or cancel this screen and convert your current site back to normal mode (Web | Network Setup | click the 'Convert' button - note that you will have to enter some network settings to 'OK' this window) and then license the new site.
You can either register for some new trial space (http://trials.sellerdeck.co.uk/) and enter the username and password that is supplied or cancel this screen and convert your current site back to normal mode (Web | Network Setup | click the 'Convert' button - note that you will have to enter some network settings to 'OK' this window) and then license the new site.