When you initialize the Offramp Widget you can pass a partnerUserId parameter to associate the transaction created during that session with the ID. You can then use that ID in this API to retrieve that transaction and any others that share the ID. The value of the partnerUserId param can be any string you want e.g. the ID of the user in your app, a unique transaction ID, or a combination of values. Anything that is meaningful to your app.