Facebook charges me for Reach even though the ad is Website Conversion

Hi guys, since yesterday I created 2 Facebook ads (Website Conversion) and I chose the conversion to happen when someone purchases something! I activated my pixel and it appears as being Active in my Facebook ad manager, so this is not the problem.

The thing is that I get charged for Reach, even though I should be charged only when someone purchases something, right? Why do I get charged for Reach? Can someone that has experience help me out? Thank you!