Will the Premium subscription work across multiple devices?
The subscription to the Premium Account is connected to the Apple ID. The Premium can be used on several devices in case of being logged in to the same Apple ID for which the purchase of the Premium was made.
It is possible to configure Family Sharing for several Apple IDs: How to use Family Sharing in iOS applications.
Transferring business cards to another device can be realized through a backup in the BCR application: Saving a backup copy of the Cardholder in BCR for iOS. If the business cards database should be the same on both devices, we recommend saving a backup and restoring it in BCR periodically on the devices.