Need iPhone app to save loyalty cards etc

I used to have Key Ring. It lets you scan the card and allows you to keep the picture of the card as well as creating a digital card.
iPhone also has the Wallet feature where you can get the electronic membership cards and keep them via Wallet.

There are websites where you can create passbook cards, some work, some don't, but it's worth trying.

You need to give examples of your loyalty cards. Traveling wise your hotel, car and flight loyalty shouldn't be a problem with them attached to your accounts. Only other loyalty cards I use are for Racetrac and priority pass which both function in the wallet.