The account submission limit is not measured by day.. but instead by the number of submissions.
For example, for FREE subscribers, the limit for submission is 100 per Month. Depending on how the form submits, it is possible to exceed the limit in a day.
You can read more details in the JotForm Pricing page here
BUT just in case you might be asking about a feature of JotForm -- the Form Limits.
Check this user guide -How-to-Limit-Submissions-in-a-Form
You can set a submission count limit so that the form will stop accepting submissions once the limit is reached.
You can set an expiration date limit (i.e. for a day only) so that the form will only accept submission up to a specific date only
Hope this help. Let us know if you need more assistance.