The trial is only active for a limited time, and a nag screen asks for a Product Key every time you open it. All of Visio Pro's features work, but you can't save or modify files.
Visio Professional is available in a free but limited trial version. Visio is part of the Office suite and integrates with it in Windows, but it's not included with most Office editions it comes in separate releases in several versions. With an extensive array of top-quality templates, Visio is both easy to use and sophisticated enough for professional applications, much like Microsoft's other Office tools. Microsoft Visio is a professional drawing tool for creating charts, graphs, diagrams, engineering drawings, networks, layouts, and schedules to use in reports, documents, and presentations.