As Gfk said above, upgrades are available from 'Account' > 'Product updates'
http://www.blitzbasic.com/Account/produpdates.phpYou can get the latest Blitz3D update from
http://www.blitzbasic.com/file/get.php?file=/Products/updates/blitz3d/Blitz3DUpdate199.exeYou will need to install that update package on top of an already installed full version of Blitz3D which is version 1.64 or higher. You can check the version number by running the Blitz3D IDE (editor) and clicking the 'Help > About Blitz3D!' main menu option.
If your version of Blitz3D is lower than 1.64, then you will need to download and install the latest full version, which you can get from
http://www.blitzbasic.com/file/get.php?file=/Products/updates/blitz3d/Blitz3DSetup164.exe . Backup and then uninstall your old (pre version 1.64) version of Blitz3D before installing the new full version. If your old full version of Blitz3D had a 'userlibs' folder in the main program folder, then you will probably want to copy and paste the old userlibs folder into the new Blitz3D program folder.