User blog comment:Crimson Storm Mich/Future Units Preview v2/@comment-30462510-20170322150923/@comment-31529105-20170324050913

From my experience, it never has. If you want to be certain you keep your progress, you can connect your account to facebook if you haven't already. The gumi support team told me to do that as an exctra precaution, so it's most likely the best way to secure your account.

Also, if by any chance you DO lose your account, don't worry. Your account is quite hard to delete, so If you can't access it you can contact the Gumi's support team and they will be able to help you out. I lost my account once, so I cn say from personal experience that they know what they are doing.