Each Shopify store is billed independently under its own card-on-file in the Redo app. When you acquire a new brand, your analyst will scope it as a separate install (same per-order or monthly model, same month-to-month terms) and you can choose whether to run the new brand's experiments under the same analyst or assign a different one.
How does billing work if I add a newly acquired brand to my account?
Multi-store and acquired brand setups.