I don't know about a liftetime membership. They have two types of plans the freedom plan and subscription like the spot. The freedom plan you pay a yearly fee and when you use it you can purchase a subscription for a month and they have varying levels with different features like you get X amount of texts, unlimited preset messages, you have so many minutes between tracking points, etc... Then when you don't use it you just deactivate it and don't pay for subscriptions until you use it again.
The other type is just monthly subscription, I think it's cheaper but yeah you need to pay monthly.
Also we had a rider go down in Baja, you can use the Inreach like a satellite texting device. Mexico has really spotty cell reception so I was able to communicate with Cabrito Inreach to Inreach. You can also pair it with your phone and text that way also, basically turns your cellphone into a sat phone sorta.
The tracking feature is pretty nice, I left mine on when I was moving during the Trans America Trail