Knowing ( or at least having a rough estimate of ) what your Customer Acquisition Costs (CAC) and your Customer Lifetime Value (LTV/CLTV) is crucial while picking the right marketing channels to go with and will determine your profitability across channels.
Customer acquisition cost is the best approximation of the total cost of acquiring a new customer. CAC, in other words, refers to the resources and costs incurred in order to acquire a new customer.
A bit more in-depth on CAC:
Customer Acquisition Cost (CAC) - Definition, Formula, and Example
Life Time Value or LTV is an estimate of the average revenue that a customer will generate throughout their lifespan as a customer.
This ‘worth’ of a customer can help determine many economic decisions for a company including marketing budget, resources, profitability and forecasting. Along with MRR, it is a critical statistic in subscription-based business models (Monthly Recurring Revenue).
A bit more in-depth on LTV: