LykkeWallet application is using so called MultiSignature 2-of-2 addresses to store client's Bitcoins. 2-of-2 means that there are two keys needed (both client’s and Lykke's) to spend Bitcoins from the wallet address. Even if Lykke is compromised client’s Bitcoins can not be spent without asking the client’s signature.
Client is also not able to spend bitcoins from the LykkeWallet address without Lykke's signature. So to guarantee safety of client's Bitcoins Lykke generates refund transaction that transfers bitcoins back to client's address in 30 days. More see about MultiSig addreses here: https://en.bitcoin.it/wiki/Multisignature
Receiving and Broadcasting the Refund Transaction
Currently if the refund address is set under Settings → Refund Address (iPhone, Android may be a little different) after each operation an email should be received containing the hex for refund. After 30 days the refund transaction signed with the client key could be broadcasted to bitcoin network (for example using Bitcoin API sendrawtransaction or https://blockchain.info/pushtx or https://blockr.io/tx/push)
Currently the above refund method works for Bitcoins.