We do not store any information in our systems about your billing information. All of it is stored in the highly trusted and certified Addon Payments service.
As it is described in Addon Payments security statement, they are compliant with the Payment Card Industry Data Security Standard («PCI DSS» for short) version 3.1. This is the highest level of PCI compliance. Moreover, all the billing information that is stored is also encrypted and is sent via fully certified and approved financial institutions. To conclude, Addon Payments provide a secure, robust and reliable payment processing service.
On our behalf, we just keep unique references to the information stored on Addon Payments Servers. Those references are also encrypted under the Advanced Encrypted Standard (AES). Most importantly, all the security is ensured by our Database System.