FYI, if you currently pay for FreeTime Unlimited it would be wise to buy this since it comes with 1 year of FreeTime Unlimited which normally costs $2.99/month.
FreeTime Unlimited $2.99 x 12 = $35.88
Echo Dot price w/1 year F.U. sub = $39.99
Net cost= $4.11
What happens if you activate it then sell it? Do you lose freetime when the next person activates it?
I’m not 100% certain but I’d say you would continue to retain the 1 year subscription. It’s the purchase of the Dot that qualifies you for the subscription. The Dot itself is not required to use the FreeTime service. In fact once you activate the service you can use it on any supported device such as regular Kindles, Fire tablets, other Dots, and compatible Android tablets or phones. Side note, just because this is advertised as a kids for doesn’t mean it is limited to be used as such. The Freetime Unlimited service can be enabled/disabled at will through the device setting which is also how once subscribed you can turn the same service on other Dot devices.
The real question is whether the person who bought it from you would receive the same benefit.