GP Limit Choices is a Gravity Forms plugin that allows you to limit how many times each “choice” on a multi-choice field may be selected (e.g. Radio Buttons, Checkboxes, Drop Downs, etc). It works with Product and Option fields with these input types as well.

This perk enables you to specify a limit per choice on your multi-choice field. If a choice reaches its specified limit it will no longer appear in the field on the front-end. While the choice is visually removed from the frontend, it is still editable via the Form Editor so the limit may be adjusted.