BeMob is one of the most popular tracking tools among affLIFT members because they have a great free "Basic" plan. They give you 100,000 events (clicks) per month for free.
They're also currently doing a promotion where you get 1,000,000 bonus events just for signing up. If you ever go over the 100,000 free monthly events with your Basic plan, you will not be charged because you have 1,000,000 extra free events.
On top of that, if you use the promo code AFFLIFT50 when you sign up for BeMob, you will also have a $50 credit added to your account!