Yes, stress does have an impact on memory. Some increases in stress hormones may improve memory performance and increase alertness and attention capacities. However, high levels of stress hormones decrease memory performance.
Stress hormones have the capacity to reach the brain and to connect, among others, at the level of the hippocampus, a structure that is very important for memory. These hormones may have many different effects on memory, negative or positive. For example, everybody remembers what they were doing on September 11, 2001. On the other hand, many people forget an important detail before an exam. For a better understanding of the impact of stress hormones on memory, you may consult are section called Stress hormones and memory.
See Effects of Stress on Memory for more details.