Hello Michael,

Yes, you can if you wish.  Version 12 functions completely independently of version 11, irrespective of whether or not you 'upgraded'.

Be sure to export any v11 projects first though, using the option in Step 5 of WebSite X5.  You will need the IWZIP files which are created by this process should you ever want to work with those same projects in version 12.  So store them safely somewhere even if you don't intend to use them straightaway.

Kind regards,

Paul