With $1 purchase you were getting 1 year subscription included. Next year would be $1 in-app purchase.
on iOS was purchase, on android was subscription, after a while I think they may have switched to subscription on iOS for the people that didn't buy it.
I think they had turned to subscription instead of one off purchase after some time.
$1 per year
it was free for android and $1 for iOS users. subscription came way later..
All I know was I had Android and it was £0.99 per year, first year free. I've been using since 2009.