Methods and hardware data structures are provided for tracking ordered transactions in a multi-transactional hardware design using a counter and an indexed table. The data structure includes a counter that keeps track of the number of in-flight transactions; a table that keeps track of the age of each of the in-flight transactions using the counter; and control logic that verifies a transaction response has been received in the correct order (e.g. corresponds to the oldest in-flight transaction) based on the age information in the table.