Paid inclusion options tend to offer other perks as well, such as guaranteed revisits to update your listings (e.g., every 24 hours), guaranteed inclusion on any partners' Web sites, reporting to track your performance, and in some cases a review of your Web site to ensure its relevance. With paid inclusion you are guaranteed to be indexed by the search engine, up to the number of pages you have paid for, within a short, defined period.
Outside of pay-to-play advertising options, you will basically encounter two search submission options: Free Submission and Paid Inclusion.
Paid inclusion is when you pay the search engines for them to display you higher in the SERPS which gives you more exposure. You'll want to make sure again that you are paying for keywords that will convert.