How can I limit the number of submissions of a form?

There are plenty of ways to achieve this so I'll just list them all. Feel free to choose which one works best for your needs.

Related guides:

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

How-to-Set-Unique-Submissions-on-a-Form

How-to-Have-Unique-Question-Using-Multiple-Fields

How-to-limit-submissions-in-a-form

If you have questions, just let us know.