Recurring $6.39 Charge

I continue to get a $6.39 charge each month from Apple, but calling the number provided on my bank statement only says to go to the website to look for purchases. Did that before calling. NO purchases show up in my purchases other than the bank statement. I have Apple One Family, so I know it's not for that. I have an additional 2TB of storage and the total is different, plus I see it each month. I can't find what Apple Service this could be for.