The only case where backup has to be created with BC Vault is when you create new wallets. You will be notified in such case as stated here - Not Backed Up notification - Wallet backup flag.

Crypto hardware wallets like BC Vault only store private keys that give you access to a particular crypto currency wallet you create. The rest of the information (i.e. all transactions) is stored on the blockchain. 

There is no need to create any backup after transactions.