Hi i want user to fill the value only one time in a field

In fact i dont need people to use the same value in a field because it give them access twice to a service.

Hello! For some reason, the chat got disconnected, so I've created a ticket for your query. Please find answer to your concern below:

We have a feature named "Unique Question". It may solve your purpose as it ensures only unique value is received for a particular field.

As an example, let's suppose you are running a contest and would like to limit unique entries or values in a form. For example, you might want to accept Unique Cell Phone numbers.

Reference: how-to-set-form-limits-based-on-a-unique-question

Please give it a try and let us know if this doesn't solve your purpose.

Thank you!