Store Period Performance works like this:
First create Financial Periods
Admin > Financial Period > Add > specify relevant criteria > Close
After updating the schedule with current info, the performance up to this date will be stored.
Tools > Store Period Performance > Select financial period date as required.
Confirm storing of info.
To refer/review stored period performance data:
Edit > User Preferences > Application > Colums > Select financial periods to view > Close. Go back to Activities view > Columns > Financial Period Value > Select assigned periods > Close after applying.