How to Test your Theme Before Submitting to the Shopify Theme Store | Selling Plan

selling-plan.liquid

{% if product.selling_plan_groups.size > 0 %}
 <div>
   <label for="plans">Purchase options:</label>
   <select name="selling_plan" id="plans">
     <option value="">One time purchase</option>
     {% for variant in product.variants %}
       <optgroup label="{{ variant.title }}">
         {% for allocation in variant.selling_plan_allocations %}
           <option value="{{ allocation.selling_plan.id }}">
             {{ allocation.selling_plan.name }}
           </option>
         {% endfor %}
       </optgroup>
     {% endfor %}
   </select>
 </div>
{% endif %}