Offline. Go to Lakme saloon, tell them u have a voucher of Rs. 1500. U want to redeem them and avail some services. They will tell which services are available at that saloon. Some services are costly and need addition payment or vouchers.
Or you can simply follow the instructions u got (from rupay) while generating the RSDC lakme voucher.
Some Lakme shop cashiers/owners do not have experience redeeming them, so if they are doing it for the first time, you can ask them to generate the bill first and then settle the bill using the voucher.