If your Spine license page is showing up blank, it may indicate that your license has been deactivated. To resolve this issue, please contact Esoteric Software directly from the email address registered with your license at contact@esotericsoftware.com. They will be able to provide specific assistance regarding your license status and help you regain access.
Additionally, if you are unable to find your Spine license page, you can use the Spine License Recovery page to have the license information emailed to you again. Make sure to check your spam folder in case the email ends up there.