Limit products per month for each customer

hello every one.
we have some limitation for our store . we have to sell just 3 products per month for each customer.
in the admin page we can set max quantity per card for each customer. its not per month .
where and what should i write in then code design to handle this issue. i use nop4.1

Yes we did that in an old version. We added extra fields to product so you can define a Weekly, Monthly and Yearly limit

Essentially you need to look at all the orders for the customer where they purchased the item they are intending to purchase.
Then have a limit set somewhere. Either hardcoded in settings if it is the same limit for all products
Or alternatively you could use the GenericAttribute feature and create a generic attribute limit for a particular product in this table  

Then you need to check the quantity they want to add to the cart with the monthly limit as set above
Then display a warning message and not let them purchase the product if it breaches the limit

You need to do this for a number of functions AddtoCart, Reorder, etc so you can add this limit check in a common place. So in the routine

        public virtual IList<string> GetRequiredProductWarnings(Customer customer, ShoppingCartType…

You would add the above check

This is some old code fragment that maybe useful

        /// <summary>
        ///     Checks the quantity to purchase for a customer is not greater than monthly limit
        /// </summary>
        ///
        /// <remarks>
        ///     Returns true if customer can purchase quantity requested
        /// </remarks>
        public static bool GetAllowedToPurchaseMonthlyNumber(Product product, Customer c, int quantity)
        {
            int limit = 0;  

                // Check Monthly Purchases
            if (product.PurchaseLimitMonthly > 0) // Can also e a setting or GenericAttribute
            {
                limit = product.PurchaseLimitMonthly;
                var dateFrom = DateTime.UtcNow.AddMonths(-1);
                var dateTo = DateTime.UtcNow;

                limit -= // Search all orders for the customer between the dates dateFrom to dateTo
                         // get the Quantity of items purchased in all the orders
            }

            if (quantity > limit)
                return (false);

            return true;
        }

thank you so much, i didn't think you answer me quickly like this.it was very helpful. -@ @-

@Yidna, if we want to do this on specific product basis, Do you think Product Attribute is more simple option than Generic attribute ?

Generic attribute requires more customization on core project

@jigarsangoi,
You can add attribute without customization, but you cannot check monthly/weekly purchase limitation using that. Even after customization, it will be difficult (except hard code or extra setting values) to identity which attribute value is used to check the limitations.

@mhsjaber Yes without hard coded value its not possible