As Shopify partners, payments for Shopify themes are handled by Shopify.
When a theme is purchased through the Shopify Theme Store, the purchase is considered final sale. Shopify theme purchases are digital goods and are subject to Shopify's platform terms and refund rules.
Before buying a theme, you can try it in your Shopify admin and preview your store with your own products, content, and settings. We recommend testing the theme carefully before completing the purchase.
For more detail, review Shopify's Terms of Service.