There is nothing like a lifetime account. I am assuming you are creating it using a particular access code - it usually stops being premium after 1-4 months.
I'm not supporting in this OP and his service. But I'm using my Grammarly account which I got it from another member as a vouch copy, and it is working fine for almost one year. But I need to wait and see after one year whether it will still continue or not. So from my experience, it may survive more than 4 t 5 months. But not sure whether all of them follow the same way of creating these accounts.
Note - I just shared my experience with a Grammarly account but not vouching this OP and his service. You guys need to make a decision.