Metadata can be used by very select use cases - usually you'd retrieve this metadata with a conversion, or add it via the API. However, we've also introduced the option to add metadata through the interface.
Below you'll find the places in which you may add metadata.
Add metadata to affiliates
Simply open your Affiliates Overview > click on the affiliate.
In the right-side panel, the option to add metadata will appear.
Add metadata to conversions
Go to your Conversions page > click on the conversion.
Int he right-side details panel, you'll find the option to add and edit metadata.
Add metadata to customers
In your Conversions page, click on the Customers tab > click on the customer.
The option to add or edit metadata appears in the right-side details panel.