Banks have limits around authorization periods. These authorization periods differ by card and can be extended periods for Shopify Plus merchants. See Shopify's documentation here.
If a merchant does not take any action on an order, for example in the scenario in which a shopper decides to keep all the TryNow items, TryNow will automatically capture payment on the full authorized amount after the items have been delivered, the trial period is complete, and the return period is also complete. These values are defined in the Trial Plan settings in Merchant Portal. To give a specific example, let's say a shopper places an order on January 1st. The items get delivered on January 5th. If the merchant has defined the trial period to be 5 days and return period to be 14 days, TryNow will automatically capture the authorized amount on January 5th + 5 days + 14 days, or January 24th. If the merchant takes an action prior to this date, such as processing a return and capturing on a different amount on January 20th, then this automated capture will not occur.
Banks will re-authorize if the authorization period is reached but the payment has not yet been captured. For example, if a shopper uses Discover, which has a 10 day authorization period, but the shopper is still in the trial period at this time, then the bank will re-authorize for the same payment. The shopper receives a communication over email notifying them that the re-authorization is about to occur:
On a shopper's credit card statement, this appears as a new authorization, while the old authorization will be void or will fall off. There may be a short period of time (24 hours) in which the shopper may see two authorizations - this is due to bank processing delays, as the bank adds a new authorization and is in process of voiding the old authorization.
What happens if the re-authorization fails?
If the re-authorization fails, it typically means that the shopper does not have sufficient funds or there is an issue with the payment method initially provided. Therefore, TryNow captures on the original authorization to ensure that we do not completely lose out on funds to charge before the original authorization expires. This reduces risk for the merchant so that we can ensure there is always an authorization that we can capture on.