Of course, stress does affect the memory. And the reason for this is not far fetched, because whenever somebody is tired, the memory part of the brain would greatly be affected temporarily until the normal state of is restored. Obviously, we can't underestimate the effects of stress on the human brain.
Basically, stress is not only the cause of memory problems, but also making causative factor of other health related issues such as anxiety, insomnia, depression, just to name a few. However, stress affecting the functions of the human memory is as a result of certain chemical hormone called cortisol(also known as stress hormone). The elevation of this hormone simultaneeously decreases other feel good hormones such as endorphine and oxytoxin that are responsible for proper worikings of the memory. This mechanism is enough to trigger stress that would inevitably lead to memory problem.
In conclusion, for stress not to hinder the rate we make use of our memory, we must learn to engage in streneous activities with moderation. And relaxation should also be incorperated into our daily lives, especially after stressful days at work place.