How long does the data keep?

Wondering about information I am gathering for my forms.

Your submissions will stay in your account until you decide to delete them, now, since you have a free account you will be able to keep 500 submissions only, when you pass the limit the oldest submissions will be automatically deleted. 

You could upgrade your account to avoid this and keep unlimited number of submissions: https://www.jotform.com/help/331-How-to-Upgrade-My-Account