only allow survey to be taken once per person

Hi,

You can put a limit on the form, you can use the following methods:

http://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question

http://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

Thank you!