Different types of end-user metrics

Typically, metrics in software are meant to mean something related to capturing lines of code, number of defects, or some other measurements related to software quality. User metrics is something entirely different, meant to try to capture data relating to the customers usage of the software. The advantages that you get out of such capturing end user software metrics are:
1. Capturing such metrics helps in validating design principles: Say both product management and engineering feel that the implementation of a particular feature is the defined way to do it, but after looking at user-functionality usage metrics, you find that the usage of the feature is lower, then some re-thinking needs to happen.
2. Helps in capturing problem areas: Suppose there is logic in the system that it reports every time that the application gets into an unstable or incorrect position (for example, if there are some parameters being passed to a functional that was deemed unlikely), then you know that there is additional work to be done in these areas.
3. Finding priority areas: Reviewing user-functionality usage graphs can be help you find which are the functions that are the most used of the application. Sometimes, product teams get surprised when they review the usage metrics for their applications. Supposed you are the team for a photo editing software, and you expect that some of the editing tools would be the most popular; and then you find to your surprise that a simple tool such as a Quick Fix tool is the most popular. Such data helps you determine the areas that are important to users, and what you need to fcous on.
4. Determining poorly designed workflows: If you have metrics in place that determine how long a users takes to complete a particular workflow as well as how many people have abandoned the workflow, you get an idea of how simple vs. badly designed a workflow is. A poor workflow would leave users spending far more time on that workflow, or even pressing 'Cancel' to leave the function in frustration.
5. Determining which features to drop. Sometimes there are features in a software that are built with a lot of hope, and do not live up to the promise. In addition, there are other features that have outlived their usefulness and need to be dropped as part of a periodic cleaning of the application. Such end user metrics can help a lot in determining the features that need to be removed.
6. Determining license usage. In the case of softwares that are available as floating licenses or as enterprise softwares, capturing of usage information helps in determining whether the pricing of such software is correct. Such metrics also help in determining whether there is any violation of licensing terms.