Approach to measure RoI

I need a professional who can help me to develop a comprehensive model for measuring return on investment (RoI) through the use of analytics. We run a web e-learning platform where our customers are businesses who buy our subscriptions to teach language training courses to their employees. We invest in talent development to make our courses better. We are looking for a presentation which can now help us in tracking RoI and an approach to enable decision makers. Looking at below specific questions to be answered: ● Main metrics to track and approach to measuring ROI ● Different use cases or objectives and their potential impact on ROI ● Determination of cost. Any other potential factors? ● Feasibility ● Utilization of external data points Applicant should specifically provide: - Detailed project proposals outlining the approach to the project, methodologies to be used, timelines