Yes you can.
You can set a Daily Budget, this will ensure you will not spend more than you wish a day.
It requires a monetary value, so if your campaign was Worldwide at $1 CPM and you wanted to get 100 visitors a day, you would set your Daily Budget to $0.10.
Please do not confuse a Daily Budget with repeat payment. The advertising payments are manually made by yourself and we cannot automatically take any money from your PayPal account.
Setting a Daily Budget also ensures your traffic is evenly spread out over 24 hours and not sent in a very short time period.
To set the Daily Budget in your account, please click on the little wrench icon by the campaign. Then enter a figure next to Daily Budget and finally, click the Update button.
The Daily Budget is set to GMT timezone, so the best way to use is to set it just once a day to make sure that traffic will be sent as evenly as possible.