Today, I am sharing with you a great Add-on to use on Google Forms. This is called FormLimiter and once installed will enable you to automatically limit the number of responses for a form you created. It basically sets "Google Forms to stop accepting responses after a maximum number of responses, at a specific date and time, or when a spreadsheet cell contains a specified value."
FormLimiter is especially useful for creating time-bound assignments, event registrations with limited seats, quizzes and many more.
Here are some screenshots provided by the developer to illustrate what you can do with FormLimiter:
1- Maximum number of responses
Form evaluates on each new submission and shuts off once a limit has been reached.
2- - Specific date and time
Timer will shut off form on that date, down to the minute.
3- Spreadsheet cell value equals
specify a spreadsheet cell (e.g. "Sheet1!A2" in the form destination sheet that must equal a particular value, and the form will evaluate on each new form submission.