The ID of the target loyalty account. Optionally specify this field
if your application uses the Orders API to process orders.
If specified, the
promotion_points field in the response shows the number of points the buyer would
earn from the purchase. In this case, Square uses the account ID to determine whether the promotion's
trigger_limit (the maximum number of times that a buyer can trigger the promotion) has been reached.
If not specified, the
promotion_points field shows the number of points the purchase qualifies
for regardless of the trigger limit.