Check your PayPal billing agreements
Written in 2014.
If you are a PayPal user you should be aware of pre-approved payments (aka billing agreements, aka recurring payments). Some of the payments you make with PayPal create a billing agreement that allows the merchant to bill you automatically. This is a handy feature when you use a service like Spotify that is billed monthly. But a billing agreement is sometimes created even if you make just a one-time payment!
I just checked my billing agreements list and there were a hefty list of them. Some of the agreements were several years old and I couldn't even recall the merchant's name anymore. As a precaution I cancelled all but those that are really current and for a recurring monthly payment.
You can check your billing agreements by logging into PayPal and navigating to “Profile → My money → My pre-approved payments → Update”. A list of agreements is displayed. You can click on an agreement and then click “cancel” to cancel an agreement you longer wish to keep active. Here is a nice visual guide how it is done.