Multiple AJAX requests using the same ajax_object.ajaxurl

To clarify your doubt you localized variable will contains the same values until it is overriden.

In your case EMX.ajaxurl will be available throught the script. Ajax not happening at your intended event might be due to not executing the ajax function but definetly not due to EMX.ajaxurl. EMX.ajaxurl will contain the ajax url.

EMX.ajaxurl can be used for multiple times unless it is overriden. So I guess you are not calling you ajax function at the intended time correctly. You need to execute disable_forms_ajax(), available_coupons_ajax() whenever you wanted to make the ajax. Also please make sure is there any script error that prevents from making ajax.