What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
To do it, first click on the widget and then click on the wizard icon:
Once you're on the wizard, you should find the option to set a max and min selection, there you should set up 1 as max selection.
Once you do that the widget will allow to select only one available ticket, other options will not be available.
Here's my sample form: https://form.jotform.com/62364965575974
Hope this helps.