title: php - Woocommerce - users can buy only one product
body: <p>for a project I want to create a webshop that offers six products.
  A user can then go to the site and choose only one of the six products.
  Once the product is selected, the user is immediately forwarded to the checkout and should only be able to order by mail.
  once the order has been completed, the user should no longer be able to order.
  That means, the email address should be saved and should be recognized when the user tries to order again.</p>
  
  <p>Is there a plugin or code to help me?</p>
  
  <p>The page is already up and I just need a solution for the checkout.</p>