Hello
At the age of 30 years, the problem of memory retention usually occur due to impairment in attention and concentration
Which may be due to following reasons
1) your brain is preoccupied with something else mostly and you don't attend things properly
2) your brain doesn't consider it important
3) in psychiatric problems like anxiety disorder or depression
4) deficiency of certain vitamins like
vitamin B12 may also cause impairment of attention and concentration
Next Steps
try to increase the focus by meditation and Deep breathing
eat healthy nuritious diet
Health Tips
if problem doesn't seem to be improving consult a psychatrist