On the APIs page, click on the API that best fits your app. New versions and APIs are always being developed, check back for updates!
Then select a plan and on the next page click subscribe.
There will be a pop up listing your Apps. Click the radio button next to the App you would like to subscribe to the plan with and click Save.
The following success message will appear when you subscribe your app to the Digi-Key API:
You can confirm your current subscriptions on the App's detail screen where subscriptions will appear on the bottom.