To keep this example simple we're using your Azure API Management subscription key to provide access to Azure API Management.

To find it: go to your API Management, click on "Subscriptions", and copy the Primary key of the "Built-in all-access subscription".

Remember: this just keeps our example simple. Do not share this key or include it in your bundle.
Instead, secure your Key Vault API with one of the many best-in-class security features offered by Azure API Management.
For more information please refer to this document.