Great post on the usefulness of cohort analysis (or of experimentation more broadly, which if you think about it, is exactly what cohort analysis is - it just uses the past as a control).

One thought on ways to analyze the follow-on problem of customers canceling after 61 days (a problem similar to what I've seen at every web company I've ever worked at).

First, perform the same cohort analysis you’ve already done, but look at the cancelling customers vs retained customers at day 1, day 15, day 30 and day 45, then use this analysis to figure out your triggers (things like # of Facebook posts needed by day 15, % of profiles claimed by day 30, etc).

Once you have your triggers, you can make proactively calling / emailing problematic customers a key part of your daily routine. While discounts might still be the way to go, this trigger based approach is one I've seen work well. Additionally, because you are in touch with problematic customers it often gives you insight into what do next.