Once an investment is made, investors use several metrics to measure the startup's success. These include key performance indicators (KPIs) such as customer acquisition cost (CAC), lifetime value (LTV), and monthly recurring revenue (MRR). Growth rate is another critical metric, reflecting how quickly the startup is expanding its user base or revenue. Customer retention rates also provide insights into the product’s stickiness and user satisfaction. Moreover, investors look at the startup's ability to meet milestones and achieve the objectives outlined in their business plan. Regular updates and transparent communication help maintain investor confidence and support.