What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Submission storage is nothing but the number of submissions being stored in your JotForm account. I see that your account is currently having 309 submissions. Since Free accounts can store up to 500 submissions, your account is good in standing. If you want to clear the storage space, you'll need to delete the submissions from the forms in your account. Also, please be noted that the deleted submissions cannot be restored in any way and the action is permanent.
Hope this information helps!