Check your purchase history, and see if there is a listing there. See your purchase history in the App Store or iTunes Store - Apple Support
When you mention you have no subscriptions, I'm guessing that you have looked at the directions here, View, change, or cancel your subscriptions - Apple Support
Is it possible that you have subscribed to Apple Music? If so, see this about changing it if you do not wish to have it. Manage your Apple Music subscription on your iPhone, iPad, iPod touch, Mac, PC, or Apple TV - Apple Support
Is it possible that you have increased your free iCloud storage to a paid subscription? See this. Downgrade your iCloud storage - Apple Support
Otherwise, you may need to contact iTunes Support. See this for an unfamiliar charge. If you see 'itunes.com/bill' or an unfamiliar charge on your statement - Apple Support