Somehow I never trust "lifetime plans". Let's call it experience 
Why would you trust any plan for that matter? 
I am taking everything with a bit of suspicion and I know everything can collapse at any moment, so I won't fall in depression that easy.
Even the most trusted vpn service could be selling your data to government without you knowledge and claim they have ''zero log policy''.
Most lifetime plans I saw for vpn are not really lifetime and you need to to some free action after few years to renew it.
What if the provider goes bankrupt, is shutdown, leaks data, complies with data requests, changes their privacy policy, etc., and you are locked in to a lifetime contract?
This could happen with any business, you could sign a contract with bank, take a credit for apartment, and it can all fall apart.It's not like you would paid huge amounts of money for vpn, that you would need to cry or call for lawyers after that
And there is the principle of it to consider as well. Once you've paid for a lifetime contract, then the VPN provider has less incentive to provide you with a good service to keep you as a customer.
Lifetime deals are only temporary, for limited time and for closed circle of people, so we are not talking about millions of customers per se