You are sure that it was a genuine email from Apple and not a phishing attempt trying to get your account and payment details ? (Not sure which apps have a subscription with that name, but a quick internet search has found one called 'Guitar! bysmile'.)
Phishing and similar emails : Phishing & Other Suspicious Emails
Phishing emails : Identifying fraudulent "phishing" email - Apple Support
Genuine iTunes emails : Identifying legitimate emails from the iTunes Store - Apple Support
And nothing shows with that, or a similar name, on your account's purchase history : See your purchase history in the iTunes Store - Apple Support ?
If it is a phishing email you could forward it to Apple : reportphishing@apple.com , and then delete it.
If it's a genuine email you could try contacting iTunes Support and see if they can find it on your account