When you backup the wallet.dat file to a cloud storage and then stake for a long time not bothering about change addresses, you can lose part of your money after restoring from your backup. There are 100 pregenerated keys in client's keypool. Every new address used for change is taken from there. When all 100 keys are used, new ones are generated, but your backup doesn't have them. To avoid it, backup your wallet.dat regularly and do not use excessive number of addresses. You can also start your wallet with this command /path/to/wallet-qt -keypool=1000, or add this line in the HyperStake.conf file: keypool=1000. If the wallet is encrypted, additional keys will not be created until the wallet is unlocked. To check your keypool size, use "getinfo" console command.