eLicense for Cubase SX 3

Am using 10.5, but have older sons which can’t be loaded in. Requires SX 3 to convert them which I own and have the original box and contents including the cardboard codes. The eLicenser code
shows the product, but wants to see the prior version as it’s an upgrade. What to do. Steinberg
support is no help.

Hi and welcome to the forum,

You don’t need any code. With Cubase Pro 10.5 license you can start Cubase SX 3. Just plug the USB-eLicenser, please.

See here: Installing SX/SE3 on W11 - #3 by keekoo
Also, search the forum for other suggestions.