Google AdWords is a self-service ad system that allows your ad to show on Google search and on its partner sites network. It works on the principle of recharging credit.
How Adwords works?
First, you need to get a credit that will be deducted based on the number of clicks on your ad. How long the credit will last is very individual. It depends on the attractiveness of the keywords for which the ad should appear. The more attractive they are, the more they cost a single click. Each user can set their daily budget. When it exhausts, the ad will stop running on that day. This gives you a full view of the cost of your ad.
Learn more about creating an account on Google Adwords help pages