How can I stop sales on an item when I reach the limit of widgets I am selling?

I have a form for a convention and we are limited on the number of dinner and breakfast meals to sell.

It would be nice if I could set the form/field to allow only a TOTAL of 250 sales.

They is probably a way but I don't know how to do it after taking a few looks at this. 

Unfortunately, the payment integration field is not having the feature to limit the quantity of products. However, this requirement can be achieved by using Inventory or Ticket Purchases widgets. With this method, the pricing calculation needs to be done manually using a Form Calculation widget and the total shall be passed to the payment field for processing. 

Please refer to the guide below that can help you with achieving this requirement.

https://www.jotform.com/help/426-How-to-Setup-a-Payment-Order-Form-with-Limited-Stocks

Hope this information helps! Please get back to us if you need any further assistance. We will be happy to help.