Erin Rollenhagen, president of Urbandale-based Entrepreneurial Technologies LLC, will provide a short course in software purchasing at the Business Innovation Zone luncheon on Aug. 21. Rollenhagen will provide advice for business people responsible for custom software purchases. The event will take place at 11:30 a.m. at the Greater Des Moines Partnership, 700 Locust St. Registration is $15, and can be done at