All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If you buy a bottle of perfume, for example, and get something extra along with it for free, it is permissible to buy it and to take the present or benefit from the service. The transaction does not involve any gambling or betting. Accordingly, the purchase is valid and taking the present or benefiting from the free service is not Riba.
Allaah Knows best.