You may not even be aware but there are various websites which have been hacked over the years where your email address (plus password and other information) was made available and personal information sold over the internet.
HackCheck is a simple tool where you can load your email address and then the tool will go to work and check for potential hackers who have compromised your details. Simply insert your email address and immediately HackCheck will check a database against known hacks and inform you if you have been compromised.
We think HackCheck is using an external database such as the free "Have I Been Pwned" and their Pwned Passwords API to check your email against their database. For example, enter your email address on the "Have I Geen Pwned" website and you get exactly the same information presented to you by HackCheck. With this in mind, HackCheck really ought to be made freeware, not a commercial tool.
There are some advantages of using HackCheck. It will run in the background and constantly monitor more than one email account. Reaction to a hack is everything. It's essential if your email is hacked you quickly change your account details and password.
You can get exactly the same results via the free "Have I Been Pwned" website, so HackCheck should be freeware, so hard to justify the commercial payment. But, if you want a tool to sit in the background and check multiple email addresses, this is the tool.