HELP-Unable to activate Cubase Pro 10.5 due to licensing error

I bought a Yamaha MODX synth, which had a download of Cubase 10.5 AI. I installed this and activated it.
I also bought the Cubase Pro 10.5 upgrade, from AI 10.5.
I downloaded the software and activation code for pro, and during a transfer of the Cubase AI license, to the USB Licenser, the e-licensing software has lost the Cubase 10.5 License, whilst transferring it to the USB licenser device.
Also, I am unable to activate the original Cubase AI because the activation code has been used.
The internet connection on the machine is fine.
This means I now cannot upgrade to the software which I have purchased, and I have also lost use of Cubase AI, leaving me with nothing.
This is not very good service Steinberg! I have paid you money and now I am unable to use your software!
How can this be remedied please?

Welcome to the forum

I can’t make out the order in which things took place in your narrative-- but it’s probably fixable. Especially if you had registered the AI license in your Steinberg account.

If you were in the process of moving the AI license to a physical USB key for the purpose of then activating the Cubase Pro 10.5 upgrade, you could not have lost that upgrade activation. In that process only the AI license gets moved, and no activation code is entered.

The next step you should take to fix this, is to plug in the USB key and run ‘Maintenance’ in the Elicenser Control Center.

Then, observe what licenses, if any, are displayed.

Here are two articles that cover this type of thing: