People were staying too long in the free tier of 10 repeating tweets, our biggest differentiation from the likes of Buffer at the time. The number of people converting to paid was flat.
I wanted to provide a generous free tier so users would become dependent on the service and tell people about it. That worked to some degree, but it was too generous.
That's why I cut the free tier in half. Since then, conversions to paid users have steadily been rising over the last few weeks.