3D FlipBook - Already paid for a year, can't get the new update, it says Forbidden

Hello, I have no idea where to put in the license key and how to get the new update. When I try to update the plugin it says that it is forbidden. I deleted the plugin and then reinstalled and now it only shows the lite version. When I click 'go to pro' it brings me to the page to pay. I've already paid. Please help resolve this issue.