Disable form on count of field?

Could you please provide us details about your concern? If you wish to disable a form based on the number of submissions it received, then you can follow this guide: https://www.jotform.com/help/137-How-to-limit-submissions-in-a-form. 

You can also disable forms based on a unique question of your submissions, here's another guide for that: https://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question.

If I misunderstood your concern, please do provide us more details.