Once you’ve paid for eight months of Premium + Sync in all, the Premium features stay unlocked for good at no extra cost, even if you cancel later: everything except syncing, backup and household sharing. The months don’t have to be in a row, and a year counts as twelve, so buying Annual once is enough.
Premium kept this way belongs to your Menu Planner 2 account, so it stays on every device you sign in on. Months you paid for on different devices count together. Without signing in, a device keeps it only from what was paid for on that device.
Only months you paid for yourself count. Premium + Sync that reaches you through someone else’s subscription, in a household or through Family Sharing, doesn’t.
Sync, cloud backup and household sharing stop when the subscription ends.