The serial number of version 2 starts with F.The serial number of version 3 starts with G.The serial number of version 4 starts with I.The serial number of version 5 starts with J.The serial number of version 6 starts with K.The serial number of version 7 starts with L.The serial number of version 8 starts with M.The serial number of version 2013 starts with N.The serial number of version 2014 starts with P.The serial number of version 2015 starts with Q.The serial number of version 2016 starts with R.The serial number of version 2017 starts with S.The serial number of version 2018 starts with T.The serial number of version 2019 starts with U.Make sure they do! Read your e-mail with your license codes carefully! Your serial number and authorization codes don't match the SketchUp Pro version you are trying to authorize (2017, 2016.One of following situations could apply to you: