How do you establish a process around measuring a launch success and what KPIs would you suggest?

Retention would always be the top of my list to monitor around a launch. This simple view of whether or not customers are sticking around will tell you more about the success of your product than even revenue or customers in.

For example, think about products like Threads that brought in hundreds of millions of users, but very few stuck around after months of usage. While many products have had explosive growth, it can be temporary. Retentive customers can most likely be monetized or grown over time, so ensure your product usage stays high, and your return or bounce rate from the product is low.