At this point, you would update to Cubase 13 Pro, though your updated licence will allow you to use Cubase 12 Pro if you wish.
Buy an update from Cubase 9 Pro to Cubase 13 Pro. Install Steinberg Download Assistant and log into your My Steinberg account. Redeem the Download Access Code you bought using the button in the top left of the Steinberg Download Assistant window - this will go through an upgrade process that turns your Cubase 9 Pro licence into a non-upgradable Cubase 11 Pro licence on your USB eLicenser and deposits your Cubase 13 Pro licence in Steinberg Licensing.
You can then download your chosen version of Cubase Pro using Steinberg Download Assistant. You do not need your USB eLicenser connected to use Cubase 12 or 13.