Every platform that offers pay per click advertising has their own ways that they handle their advertising, traditionally there are two major types of ways you pay for your campaigns. Most sites either bill you at the end of the month (or when you reach your preset limit) or you make a deposit and pay in advance where money will be withdrawn as people click on your ads until your balance is zero. Depending on your marketing goals and advertising budgets will depend on which way of being charged is best for your company to advertise locally or globally to potential customers and clients.