Past conversions can be uploaded directly via the API by the user using the standard Server to Server integration.
Uploading data from a file is only possible in exceptional cases and may be charged extra as this is a manual task where data needs to be in a very specific format.
Important Notes: Import of past dates beyond 3 months ago is not possible due to technical limitations. However, you can change the dates of the import to reflect it as if the conversions happened this month.