Loss aversion is a common tactic used in upgrade emails sent out towards and at the end of a free trial. You can also employ loss aversion if you have a freemium model or would like to nudge more customers to higher pricing tiers with additional features beyond increased space or volume limits.
Followup.cc leans heavily on loss aversion in its upgrade email, after starting you on a free trial with premium benefits.
Given what we understand about loss aversion, this email could have been even stronger if it invoked the benefits, not just the attributes, of the premium features — reminding people that they could be losing powers to organize, be productive, and build relationships.
Read more about how you can use the psychology of loss aversion in your upgrade emails.