The memory loss with benzodiazepines occur because events/experiences are not transferred from short-term memory to long-term memory and thus not consolidated into memory storage. So there is anterograde memory loss (memory loss after consuming or starting benzodiazepine). Information stored prior to the ingestion of a benzodiazepine is not affected. This is what the evidence says.
Next Steps
There is no doubt that it causes anterograde memory loss (events forward in time to consuming benzodiazepine) by impairing short to long term memory consolidation. So, it's better to avoid long term of same if you are in to academics or any kind of learning.