How many forms is 100mb that it will store?

Please note that 100 MB is the upload limit, and it is not related to the number of forms or submissions you have. If you add "File Upload" field in form and your user submit form with file upload, it will consume space based on the file size that user upload in form. Free account has 100 MB of upload space limit.

You may like to take a look at the following guide for more information on account usage and limits: https://www.jotform.com/help/408-understanding-your-account-usage-and-limits

Hope this helps.

Do get back to us if you have any questions.