A Version Archive is provided on the Download Centre where you can find the installers for older versions of VE that you may require to complete a project.
Each VE Product has a Version Archive available so select the product (e.g. VE For Engineers, VE For Architects etc) and click the relevant Version Archive link. In here you can choose to download the installer for the version of VE you require.
These are full applications installers (not patches), you can have one version of each major VE version installed on the same machine so for example if you currently only have VE 2013 then you can download and install a VE 2012 version but if you have VE 2012 and require VE 2012 Feature Pack 1 then you must first uninstall VE 2012 before downloading the VE 2012 Feature Pack 1 from the archive.
The Version Archives are maintained by the IES Technical Support Team so if there is a version you require that isn't already available please contact the team to request it.