The SalesGoals.com site is free, as is the plugin. The plugin will place an embedded link for 'Powered by SalesGoals.com' only for free accounts. Paid users will not have a link shown on their site.
The plugin will store the SalesGoals.com account credentials in the WP database. It has a link to remove these credentials from the user from. The plugin also supports customizable fields and reCAPTCHA for spam protection.