Progress towards idiosyncratic milestones is hard to capture with metrics. Acquisition, activation, retention and monetization like metrics are offered by most services. Keep it simple with something like Google Analytics (or anything that collects the data) and compute the metrics periodically. You'll probably need to clean your data to make it useful; that's almost always easier once exported. That's the basis for an internal and external viewpoints for board discussions and decision making.
Progress towards idiosyncratic milestones is hard to capture with metrics. Acquisition, activation, retention and monetization like metrics are offered by most services. Keep it simple with something like Google Analytics (or anything that collects the data) and compute the metrics periodically. You'll probably need to clean your data to make it useful; that's almost always easier once exported. That's the basis for an internal and external viewpoints for board discussions and decision making.