The renewal period that displays is based on the assignment given to the member on their Members->Account tab. For example, a fee assignment with Annual frequency and a renewal month of August would display the renewal period “August 2011 – July 2012” when creating the August 2011 batch of invoices. Quarterly frequency with a renewal month of August would display “August 2011 – October 2011”
The renewal period will display on invoices that are created using batch type Monthly Renewal or Monthly Renewals - epayments.