Measuring KPI's

Hello,

I was wondering how everyone easily measures revenue stats with their SaaS offerings.
I’m trying to determine stats like CPA, LTV, RPU & Churn rates in relations to my users to understand the economics better.

CPA – Average Cost per user acquisition
LTV – Average Lifetime Value of users
RPU – Average Revenue per user in system
Churn – Percentile of users cancelled service (mnth to mnth or week by week)

I cant seem to find a simple plugin which tracks these & was wondering how everyone is?
Also I know there may be some manual entry in regards to cpc to derive cpa & membership price to derive LTV but there has to be a simple way to track no?

thanks