Aurrod

So it says I can buy 1 session subscription, 3 sessions and 10 sessions. Why is the 10 sessions the cheapest? Does that mean I can only use it 10 times and then have to buy it again?Or is it the cheapest because I can choose to only get it for 1 month while the other 2 options are for an entire year? Also, if the bot itself already has a "grinder" (I tested the trial and it leveled very well) why do I need to buy grinders and profiles from other people? Thanks!