I've paid $22.49 guaranteed that it will be only once.
But it says on my account that Totem Time Active Until: 2016-08-04
So what the heck is this an old bug left behind or I am missing something and I should've bought it on steam?
Totem time, (explained also here) is an optional monthly payment to keep your player and tribe active on both servers without needing to log in. Totem Time is entirely optional and is also intended as a way for players to give a bit more towards Xsyon's development.
It's not required at all. Players can log in and play indefinitely without it and you can keep your player (and tribe) active just by logging in.
Tribe totems decay in this game, you need to log in to reset the decay timer or risk your totem being deleted (used to be 90 days without activity, think it's 120 days now).
When we had subs your totem never decayed when you had a tribe member with an active sub, but without subs all tribes now decay, so the totem time is just an optional extra, a safeguard for those that don't want to lose their tribe/land if something unexpected happens in the real world.