Can I upgrade from LR 2.3 to LR 4, 5, or 6? (stand alone for desktop, not CC). Can the license from LR 2.3 be accepted?
Thanks for your reply.
Yes you can upgrade to Lightroom 6, which can only be installed on a 64-bit operating system.
See the system requirements here: System requirements for Photoshop Lightroom for Mac and Windows OS
Go to this page Software & Services and click Buy.
Then click on Full, and choose Upgrade from the dropdown.
When installing, you will need the serial number for Lightroom 2.