I'd go for a lifetime purchase of VPN. I don't like the subscription model. I feel like we're getting nickle and dimed on life.
Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.
It is not unreasonable to adopt a subscription model, since services always have maintenance costs.
I agree with @Anonymous
Unfortunately this is the new reality. One time purchase that gets you lifetime access are not sustainable in the long run for most services.