A very common error is that when customers try to add your membership product to the cart, they see the error Variant can only be purchased with a selling plan. A selling plan is the name given by Shopify to purchase options, such as memberships or subscriptions.
Simplee Memberships updates your Shopify product to require a selling plan so that customers can't accidentally purchase the product without recurring billing properties.
How to fix this issue
Try the following things to resolve this issue:
Be sure you have installed our widget on the theme your are experiencing the issue on
In Simplee Memberships, select the Installation tab
Select the theme you're updating, and click on Update Theme
Try loading the page again and add the product to your cart
If this didn't resolve the issue, then please chat with us for assistance. We will need to update your theme so that our widget appears correctly
If you're familiar with Shopify themes, you can try adding the following Liquid code inside your product form:
{% render 'simplee-widget', product:product %}