Can we upgrade and downgrade our account anytime?

2. Can we change the plan we are on throughout the year? We are a seasonal business. So during tax season we would have thousands of submissions per month. While out of season, it could be hundreds.

Yes, you could upgrade your account when you need more account limits and then downgrade your account to free again, when you downgrade the account it will get back to free status on the next billing date, for example, if you purchase a monthly subscription on February 16, 2017 the next billing date would be March 17, 2017 so if you decide to downgrade before the next billing date your subscription will be cancelled instead of renewed. 

This guide will help you upgrading your account: https://www.jotform.com/help/331-How-to-Upgrade-My-Account 

And this one will help you to downgrade your account back to free: https://www.jotform.com/help/341-How-to-Downgrade-Subscription-Back-to-Free-Account 

If you have any question, please let us know.