For HeyLight BNPL (0%) you do not need a Public API Key so you can leave that field blank if you want.

<!-- DEFINE CUSTOM TERMS HERE -->
{% assign minimum_amount = 100 %}  
{% assign maximum_amount = 500000 %}  
{% assign available_terms = '3,6,12,24,36' | split:"," %}  
{% assign min_instalment_amount = 100 %}
            
<!-- DON'T CHANGE ANYTHING BELOW THIS LINE -->
{%- if product.price >= minimum_amount and product.price <= maximum_amount -%}  
	{% assign term_ceiling = product.price | divided_by: min_instalment_amount %}  
	{% assign acceptable_terms = '' %}  
	{% for term in available_terms %}  
		{% assign test_term = term | times: 1 %}  
		{% if test_term <= term_ceiling %}  
			{% assign acceptable_terms = acceptable_terms | append: ","  %}  
			{% assign acceptable_terms = acceptable_terms | append: term  %}  
		{% endif %}  
	{% endfor %}
                  
        <div class="heidi_messaging">
          <div  
           id="heidipay-container"  
           data-heidipay="true"  
           data-heidipay-minorAmount="{{ product.price }}"  
           data-heidipay-term="{{ acceptable_terms | split: "," | last }}"  
           data-heidipay-currencySymbol="CHF"  
           data-heidipay-lang="{{ localization.language.iso_code | slice: 0, 2 }}"  
           data-heidipay-type="PRODUCT_DESCRIPTION_HEYLIGHT_BNPL_CH"  
           data-heidipay-apiKey="PUBLIC_API_KEY"  
           data-heidipay-cadence="MONTHLY"  
           data-heidipay-thousandsSeparator="."  
           data-heidipay-decimalSeparator=","  
           data-heidipay-symbolOnLeft="false"  
           data-heidipay-spaceBetweenAmountAndSymbol="true"
           data-heylight-logo-variant="black"
           data-heidipay-decimalDigits="2"
         />
        </div>
{%- endif -%}

You will also need to include the script below for both sandbox and production versions. We recommend it be included somewhere it will always load (typically the index or a footer).

<!-- FOR DEMO / SANDBOX VERSION -->

<script src="https://sbx-upstream.heidipay.io/sdk/heidi-upstream-lib.js" ></script>
            
<!-- FOR PRODUCTION / LIVE VERSION -->

<script src="https://upstream.heidipay.com/sdk/heidi-upstream-lib.js" ></script>

This script will load the promotional message.