As with any issue, using the right tool for the job can help reduce the impact of the problem. For memory problems you could carry a notebook with you always, use a tape recorder, a calendar, or if you have a smart phone you could take notes on it as well.
Ten years ago I was manic for the better part of two years. It's like a gaping hole in my memory. I don't remember much of what happened during that time. I have talked to several people with bipolar and they all have complained about memory problems. The illness itself causes the memory challenges and some medication complicates it further.