Looks like you started your paid subscription just today, so you should be able to add products now. There may have been a slight delay after starting the subscription until our system got notified of that and reactivated your expired trial account.
If you're still unable to add products, try force-reloading our Seller Admin panel by holding the Ctrl key (on PC) or Shift key (on Mac) while you click your browser's Reload/Refresh button.
