Gravity Forms Stripe Add-On was updated to version 1.8, from version 1.7.1. Changelog:

• Updated feed list and edit pages to display configure settings message if the api keys for the selected mode are invalid.
• Updated Stripe Receipt drop down to only list email or hidden type fields.
• Updated to use object notation when accessing $field.
• Updated minimum Gravity Forms version to 1.9.10.19.
• Fixed an issue which allowed feeds to be created with only partially configured metadata.
• Fixed PHP notice related to the Metadata setting on the feed edit page.
• Fixed php notice when saving a feed without any custom metadata.