How to set form limit based on multiple unique questions

please how do i make sure one applicant doesnot register twice for each form considering email ,number and name found are similar

What I suggest you do is add each field's value (email, number, and name) into one (additional) field conditionally following this guide.

Conditional-Logic-Inserts-Text-Calculation-Into-A-Field

Then, set that field as a Unique Question of your form.

How-to-set-Form-Limits-Based-on-a-Unique-Question

Here's a sample form:

https://form.jotformpro.com/71641319665965

The additional field should be hidden in the form but I left it unhidden in the sample form for testing purposes.

I hope this helps. If, in any case, I have misunderstood your concern, please feel free to contact us anytime and provide us more details.