Where is MetaFields Database?
Where is the data stored? On Shopify server or on Webify server? Is there a chance that the app goes down due to some server outside of Shopify being down?
Metafields is stored in Shopify's database and accessed through their API. So the presence of the metafields does not depend on the app. In fact, you can remove the app and all the metafields will still be there.
This question has received the maximum number of answers.