Whether your tests and results are backed up to the cloud - and whether you can restore them - depends on your account type.
If you're using CamGrader without an account, everything stays on your device only. There's no cloud backup and nothing to restore - if you get a new device or lose this one, your tests and results won't carry over. Create an account if you want your data backed up.
Signing in without a subscription does not turn on cloud backup or restore. Your tests and results still live only on your device. Subscribing is what enables the cloud backup features below.
A subscription includes automatic cloud sync, so your tests and results are continuously backed up in the background - you don't need to do anything for this to happen.
You can also trigger a manual backup at any time from Settings using Download My Data, which exports a complete copy of your account's data.
To restore, use Import from Settings and choose your exported file. If the file is a cloud export, CamGrader will also download the associated images and email you a confirmation once the restore finishes.
If you sign in on a new device, your data restores automatically through cloud sync as well - manual export/import is there as an extra option, not a requirement.