This is a setting example for Shopify to prevent specific products specified by tags from being added to the cart if the user is not logged in (registered). This is a simple way to edit this from the theme editor, but you can also embed the code directly in main-cart.liquid.
Example of setting to prevent adding items to cart on the product details screen if you are not logged in with the theme "Dawn"
[Setup Procedure] Add the "Customized Liquid" block to "Consumption Information" and insert the code
[How to use] For products that require login to purchase, add the tag specified in the code in the "Settings" section.
