Make sure when customers checkout, they are added to your loyalty program.
You can access these settings in your BigCommerce Store Settings.
BigCommerce Customer Account settings
Customers are automatically added to your loyalty program when they create a store account. They can do this by making a purchase online or by creating an account through your loyalty widget.
To make sure that customers can create a store account, check your BigCommerce Account Creation settings.
Under Display Settings, set your BigCommerce Account Creation setting to:
Yes, enable account creation in my store
Your customers will have the option to create a store account or check-out as a guest. In both cases your customers will be added to your loyalty program and earn points for their purchase.