Why did I got charge for $8

How do you know you were charged $8? Did you see it on your bank statement or website? See this Apple support article—>If you see apple.com/bill, itunes.com/bill, or an unfamiliar charge on your statement - Apple Support

If you did not see it there, did you receive an email saying you were charged? If so it’s possible that it was a scam to steal your identity. See this Apple support article—>Identify legitimate emails from the App Store or iTunes Store - Apple Support

You can also check your purchase history to find out if you were charged, and what you were charged for—>See your purchase history for the App Store or iTunes Store - Apple Support

After all that, if the charge actually appears in your purchase history and you believe you were charged in error, see this link—>Request a refund for apps or content that you bought from Apple - Apple Support. But note that you must actually have a charge on your account to request a refund for it.

Was this a charge you saw on your statement showing a charge from iTunes?

If you see apple.com/bill, itunes.com/bill, or an unfamiliar charge on your statement - Apple Support