iCloud storage

It's best to have at least one backup, either iCloud and/or computer's iTunes - if you lose the phone, or it breaks, you will losing content if you don't have a backup to restore to

Connect the device and select its Summary tab, that tells you when you last backed it up to that computer. Or go into iTunes' Preferences and select the Devices tab, that lists all devices backed up to that computer and their last backup dates