Perfect Audience charges no monthly fee. They work/charge on CPM basis and their all campaigns are prepaid for self-service customers. They bill their customer weekly based on the money they spent in the previous 7 days. Perfect Audience act as a middleman between Facebook, Twitter, and Google Adwords, and simply charge their cut/margin on your money spent on these campaigns.
They do offer a 2-week free trial, meaning they don’t take their margin on your investment on those campaigns. Perfect Audience and AdRoll are quite similar and very easy to use. Although, AdRoll has a more refined user experience, but Perfect Audience interface is not bad either. Perfect Audience does provide plenty of options to get a better insight on the visitor’s activity. If you’re getting started with Ad Retargeting and looking for a good user interface, then definitely go for AdRoll and if you’re in this market for a while and looking for an advanced play on Ad Retargeting, then Perfect Audience is a better option for you.