You can mint one ad per day for free. To increase your ad minting limit, you can purchase an Asimi Stake.
Each stake allows you to mint one ad per day for 365 days.
A minters reward is determined by their personal contribution to the network. This is a combination of how much advertising they view daily (POW) and how many Minting Packages they own (POS). The more stakes one owns, the more you can mint and the greater the reward.