Premium accounts let you update the profiles (Mailchimp, Salesforce, etc.), subscribe/unsubscribe customers from mailing lists (Mailchimp, Constant Contact, Mad Mimi, etc.), refund charges (Stripe). It's $29/month, with a discount up to $19/month when paying for a year up-front.

We haven't published the pricing information yet (it'll be up this week), but that's what we've been releasing to our beta users so far.

Happy to answer any questions!