I am also having activation problems. I purchased the latest version v18 as an upgrade. I have earlier versions, including the very first version of parallels from 2006, bought directly from parallels.com. However, the key format has changed over the years. The current format is 5 sets of 6 alphanumeric. The 2006 licence key was a shorter key (5 sets of 5 alphanumeric). The activation dialogue box simply does not accept the 2006 licence key. The 2006 key is valid and worked on my old Macbook from 2006. Please help.