Magento Module - Serail Number and Activation

I need, for a magento store, to have to each product in the user order, create a serial number based on: user id, store id and sku of the product. This serial number will be sent to the user . In the my account area, the user will see his orders and the serial numbers, with an option to activate the product. When he clicks it, we have to save the date of activation and show it to the user.