Hi Marco, I don't think you need to buy another program, but I think you may need to register another key for New Horizons..
Also, as you are Italian, this post may interest you..
HI
uninstall you game, reinstall you Italian version and You can download this fix directly from our download server via the following link:
http://80.95.161.114/get-files/ShipSim2008/patches/ShipSim2008.CE.IT.Update.exe
Please note that this fix is approx. 89MB and will only work for the Italian Collectors Edition!
TJK