Due to licensing restrictions imposed on the Software that is provided as part of product registration, Wacom is unable to issue a second software license. Registration is limited to the original first time new purchaser of a Wacom device from Wacom directly or a valid Wacom reseller. In addition, the Wacom Limited warranty does not apply for second-hand devices.
Regardless a Wacom tablet can still be used on your computer even without registration. Simply download and install the current driver. Set up and use tutorials can be found on the Wacom getting started pages.