Hello. I am creating a Gatsby store using Shopify with this Gatsby starter - https://github.com/AlexanderProd/gatsby-shopify-starter. The starter needs a Shopify app (API) key used in the Gatsby query. The app works well in development mode in my partners account and I know I soon need to transfer it to the client account when I am done. The question now is, since I do not need the online store, can the client use the Shopify Lite plan ($9) and still get to use these API keys created?
Yes, you can use the API even if a store isn't using the Online Store sales channel.
The Online Store sales channel can be removed from the "Settings" > "Sales Channels" page in the Shopify admin. If the client has already chosen the Basic($29) plan this will move them to the Lite plan automatically, otherwise if the store is still in trial/development removing the Online Store channel will allow them to pick the Lite($9) plan when choosing a plan.