As posted on Google Will Delete Your Backup If You Haven’t Used Your Android Phone in 60 Days
Android: If you’ve got an Android device, you most likely have a backup of it stored in your Google Drive account. Unfortunately, as one user discovered, that backup can expire in 60 days if you leave your Android device untouched, even if you’ve got more than enough space to store it yourself.
The potentially crippling data deletion policy completely wiped redditor Tanglebrook’s Android smartphone backup, which included saved Wi-Fi passwords and personal preference settings. They sold their Google-branded Nexus 6P, opting to use an iPhone until they could find a suitable replacement Android device. In the two-month timespan during which Tanglebrook hadn’t accessed their Android device, the backup was deleted without warning.
While it might come as a surprise to most Android users with backups, Google knows it’s treating your backup data as ephemeral when your Android device becomes inactive. According to its support page, “Manage & restore your device backups in Google Drive:”
Your backup will remain as long as you use your device. If you don’t use your device for 2 weeks, you may see an expiration date below your backup.
Example: “Expires in 54 days.”
In short, if you want to keep your phone’s cloud backup, you’ll have to poke around it every few weeks, lest it get automatically wiped.