AWS Marketplace purchases are represented in Stax alongside AWS services in the Cost and Data pages. This allows you to reliably compare usage of AWS services with those you've purchased through AWS Marketplace.
When reviewing information on the Data page, you can further refine this with the Marketplace Product property. Costs incurred as part of AWS Marketplace purchases will have a value of true, while those incurred as part of regular AWS consumption will have a value of false for this property.
Filtering on the Marketplace Product property allows you to either include or exclude AWS Marketplace purchases, while grouping by this property allows you to evaluate costs of AWS Marketplace purchases against AWS services.