I've had a nebula subscription for a couple years, and honestly I don't think the lifetime subscription is worth it. If you can find a deal on a year plan it's crazy cheap, and I don't think nebula is big enough to be certain it'll still be relevant by the time a lifetime plan would pay itself off. Maybe if it got more popular, but its place as a more specialized type of video platform, and especially a subscription based one, makes me a bit doubtful that it'll grow significantly any time soon.