The ShineOn API key is used for a few different things.
If you're looking to connect a third party application to your ShineOn account - such as Customily or AnywherePOD - they may ask you for your ShineOn API key.
In these cases, simply providing the API key where it needs to go will be all you need to do.
However, If you're a big store or POD service with a good handle on programming and development, then selling using our API to give us orders might be a good option for you.
Before making a large tech investment, you may want to consider trying out CSV Ordering first. The sign up process for both API and CSV is mostly the same, so why not give it a go?