You can never know for certain if your passwords are still stored somewhere or not, but I wouldn't worry about a billing email arriving after your account was

You can never know for certain if your passwords are still stored somewhere or not, but I wouldn't worry about a billing email arriving after your account was deleted. Many companies will retain billing/transactional data even if you delete your account. They might do this for regulatory compliance (eg.in Austria I need to store invoices for 7 years in case the Finanzamt wants to do an audit) or they might just do it as a protection against fraud or credit card chargebacks. I would assume that "deleting an account" just means "delete your data" (ie. passwords and most personal data) and does not mean "delete all information related to me as if I had never done business with you".