Hi VictorLaser,
Great Question! I would like to advise you to go to your Settings and check your bid adjustments. A common area is within the Location settings:
Ex: Targeting the United States with a Bid Adjustment of 100% and your keyword bids are $1.00. If a customer clicks on your ad in the United States, your CPC can accumulate up to $2.00 even though your keyword bid is only $1.00. If your bid adjustment is changed to 50% your CPC can accumulate to $1.50. Please note that having multiple bid adjustment can mean multiple CPC amounts.
The bid adjustments are available on the Location, Devise Type, Ad Schedule, and Demographic.
I hope you find my information helpful! If you review your account and notice that you have no incremental bidding set and continue to receive a CPC that is higher than your keyword bid, I would be more than happy to review your account. Please check your private message so I can gather more information.
Thank you for choosing Bing!