Following tonight’s maintenance, there has been a new change to the Switch eShop. Previously credit card information could not be stored on the eShop, requiring it to be re-entered for each purchase..
This has been changed , so that now when you buy a digital download, you are given the choice save your credit card information. This information will be located under your profile if store and you are also given the option to enable / disable password entry for purchases if you do choose to store the information.