Trying to figure out licensing

Long ago I purchased Vray and Phoenix FD via ToolFarm, both tied to a dongle. I have since upgraded those licenses to the online licensing.

Sorry if this is a stupid question, but I want to upgrade to Vray Next and ToolFarm asks for a serial number for upgrade licenses. Where do I find the serial number?

Sorry guys, I just found my old dongle and see that the serial is printed on the side of the dongle itself. Never mind!