2Checkout pre-authorizes credit / debit cards and PayPal accounts using minimum amounts such as $1.00 / 1.00 EUR to enable customers access to free trials and to fulfill free orders (with 100% discounts and those with 0 price set using "on the fly pricing"). This is a common industry-wide practice for e-commerce companies. Pre-authorizations are designed to ensure that credit/debit cards and PayPal accounts (the credit / debit cards associated with PayPal accounts) are valid and that the necessary funds exist to charge customers for trial conversions and subscription renewals. In addition, pre-authorization also acts an anti-fraud protection mechanism.
Authorization request between the 2Checkout system and the payment gateway or PayPal used to validate your card information do not result in money being withdrawn from customer accounts.