Formsite service levels use limits on the number of forms, number of items per form, number of results per form, and several other items of note, as well as access to specific features.
To choose your most suitable service level, first determine how many forms you will need, then consider how large your form will be. If you know that you'll need either lots of forms or forms with lots of items, you will most likely want to begin with the Pro 1 service.
Additionally, if you know that you'll need payment processing or PDF functions, you will want to look through the available features for each service level.
See all of the service levels and their limits on the Pricing page.