The transaction and code will be valid until midnight, one day later. In case the code is not used, the transaction amount will be reversed to the sender’s account, however the transaction charges will not be refunded.
For example, if the transaction is initiated on January 9, 2015 at 3:00 p.m; it will be valid till next day i.e. January 10, 2015 11:59 p.m.