Client's return so license may have been previously registered. - This license is lifetime and doesn't expire !!! Intuit QuickBooks Pro 2005 Windows CD for Windows - Retail 5 Users Version !!! + Original Installation Code This is for Windows XP or older versions however we had clients running it with Windows Virtual PC (Free) on a Windows 7 machine, I imagine it will also work with the newer Windows 10 & 11 running Virtual PC.