Bold Upsell does checks to ensure that the user's cart qualifies for the offer before allowing customers to add a free product. However, it is not (and can never be) 100% foolproof due to the way Shopify accepts products and cart adjustments.
Upsell has an option, when you go to create the offer, that will remove the free items from the customer's cart when they no longer qualify under the offer's conditions.
- Introducing "True Upsells" for Shopify
- Problem Solved: Creating upsell BOGO offers on Shopify
- How to use cross-sells and upsells to increase revenue on Shopify
- 9 upselling techniques to explode your average order value
- How to create simple upsells on Shopify
- Why upsells AFTER checkout on Shopify will be your highest converting click