This is a good tool for determining whether your account has been compromised by hackers:
That might explain a breach I had a while back.
I'm guessing someone used your email address to start a free trial in order to pirate the software. They were either replacing an older version they had, or wanted a free upgrade and attempted to hide their identity.
FYI Photoshop is one of the most pirated pieces of software.
Useful though. I doubt thats all in reality unfourtanetly.