Allow one entry per IP address
Restrict form entries by allowing one entry per IP address
Refer to this page to learn about this form property. - Open the form builder.
Click the Properties icon in the top-right of the form builder, as shown below. The Form Properties pane will appear on the right.

- Navigate to the Form Properties > Restrict Form Entries section.
Check the checkbox next to Allow one entry per IP address :

Click
I understand, Proceed in the pop-up window that appears. Refer to
this page to learn about capturing IP addresses.

Once this feature is enabled, only unique public IP addresses will be captured which means that you cannot submit two entries using the same public IP address.
Upon proceeding, the following will happen:
The Capture IP address property of that form will be enabled:

A default Error message will appear below it, which you can customize:
