The ability to back up local game saves into the cloud is a feature Nintendo has long touted as a selling point for its Nintendo Switch Online service launching September 18. Those cloud saves, however, will be lost if a customer allows their subscription to lapse.
“Save data stored with Save Data Cloud cannot be kept outside of the duration of your Nintendo Switch Online membership,” reads an FAQ on Nintendo’s U.K. website. “Nintendo Entertainment System – Nintendo Switch Online also uses the Save Data Cloud, so the same applies. However, if you keep the Nintendo Entertainment System – Nintendo Switch Online save data saved locally on your Nintendo Switch console, then you can use it again if you purchase another membership.”
Source: IGN.com Nintendo Cloud Save Data Is Deleted if Your Subscription Expires