What are intact and impaired memory functions?

Memory is complex: Intact memory functioning is complex. One needs intact attention, intact ability to form a short term memory, intact ability to move information from short term to long term memory, intact ability to form a long term memory and then ability to recall the information when you want or need it.

Depends: normal or "intact" memory usually refers to what is normal for that individual. so if someone experiences changes from their own baseline, that is considered impaired.