You need not to apply any promocode to avail any offer. The offers are based on transaction basis. In case you satisfy all the conditions of the offers mentioned on our offers page (https://niki.ai/offers/), you will definitely get cashback.
For terms and conditions of each offer, just tap on the offer you are interested in. You can go to Offers and Promocodes section of the app and then tap on View Offers for all the available offers.
In case you want to avail Uber Cab Promocode offer, you can fill the promocode by tapping on Apply Promocode. The offer will be applied for the next Uber ride you take.