Our website uses authorize.net CIM to store consumer credit card's securely after a user's initial purchase. We currently do not have an "opt-in" button allowing us to do this. However, after reviewing other sites such as Groupon, Living Social, and even Amazon, it seems as though this is now common practice. Other more traditional sites such as Nordstrom's require the user to opt-in to save the Credit card. I was wondering what best practice was for saving credit cards. Any other example references would be appreciated.
Thanks for any advice you can provide.