Zapier provides a cloud-based integration platform to help you connect all your web apps and systems to each other. They used this Free trial email sequence to promote their various Zapier plans.
This email sequence opens with a homepage where you can sign in for free. Followed by a set of more personalized emails. In these emails they walk you step by step through the process of understanding the features and benefits of Zapier. Constantly reminding you how Zapier can help you to be more efficient. The sequence ends with an upgrade page where you can chose one of their professional plans.
You can read more about Zapier here: zapier.com