why would it drop? membership costs 5usd for a month right?
so there is 12 months in a year
5x12=60
lets say if a x user buys membership for a year they would make same amount of money from that user if he had paid 5dollars each month
another thing is that some people might buy a year membership and quit pro after like 5months of playing, but still pro would have made 60usd from that, but if the user pays for monthly membership than pro would make only 25from him.
Anyway i dont see a reason why this yearly membership shouldn't be an option.
This could be implemented but the Life time thingy nope