How do I ensure a specific product variant is not available for purchase as a subscription?
You can create variant level subscription groups if you have a Shopify 2.0 theme. This feature is not available for vintage themes.
When creating or editing your subscription group, click Select products, then click on the variants displayed underneath your product. Check the box next to all the variants you want to include, leaving out the one you don't want to include in the subscription. Click confirm. Complete the rest of the setup for the subscription group, and then click Save changes at the bottom.
For more step-by-step instructions, please visit Create a Standard Subscription Group here: https://support.boldcommerce.com/hc/en-us/articles/360051203791-Create-a-Standard-Subscription-Group