The program ImageGrab that can be freely downloaded on the site of Paul Glagla is a personal version reserved for the personal or family use of the amateur of digital video. It has the same features as the Pro version and only suffers from a license limitation: Any use in a professional, commercial, administrative or associative, even non-profit context, is prohibited with the personal version.
If you need such use you have to request a Pro licensed version. This is exactly the same software as the personal version, except that it is specially recompiled to remove warnings reminding that it is for personal use only, and include the name of the company, organization or person who owns an unrestricted Pro license. A Pro licensed version may only be used in this business or organization and may not be released outside of this business or organization.