REQUIREMENTS MANAGEMENT TOOLS
The process for acquiring an RM tool is no different than selecting software packages that will be part of your development effort. First, identify requirements for the requirements tool based on your project or company needs or standards. Thoroughly investigate candidate packages for compliance with your requirements, including performance demonstrations.
Performance demonstrations are critical: you may discover add ons are required to achieve full traceability to other work products. Tests and design are part of the software product and should be maintained along with the code and documentation.
Some RM tools cover the entire development environment, and they may dictate how you approach system development. The features and capabilities of any tool you are considering should be tested to ensure it works with your development approach.
Allow time for the learning curve, which can take up to a month. Several requirements management tools below are available as free evaluation downloads.
See link disclaimer.
Walk the RM trail to learn more about requirements management and traceability. 
Take a traceability lesson from an industry expert.
Can a requirements management tool pay for itself at your company? This article looks at a model to help calculate return on investment (ROI) on requirements management tools. Read the article.