That moment when you find out that your paid app has been cracked. :/ ;_;

Check best practises, rewrite, push update.

I should point out that I have installed several cracked apps over the years but I use almost none of them (what if I ever need it? mentality).

If I was forced to pay I wouldn't bother checking those apps out.

So, if you can, monitor the pirated app to find out what and how people use it.

You may find out that people don't really use the app at all or they use it rarely or just need a specific feature.

Then you will be able to monetize your app better or swift focus.

I really don't understand the need for cracking the app.
The app is priced quite low I believe (it was lower than the minimum price I could set in some countries so I actually had to hike it up for those countries). Also, the paid features aren't that wannabe that one needs to crack it to use that. Perhaps somebody wants to bring me down?

Either way I have already started implementing some more security measures and also thinking of some unique stuff to add so it cannot be easily cracked by known methods.

Also I learnt that my sources aren't obfuscated well so that is another thing to do.

Not all people have money to spend on apps. Some aren't even able to even if they wanted.

Cracking an app shows one's skills so that's, probably, what happened.
Don't make it personal.

Or, maybe someone needed the app, had no money but had the skills.

Also, there are places one the internet where people ask skilled people/groups to crack specific apps.

Download the cracked app and try too find who did it and maybe why.

Lastly, depending on where it's hosted you could ask them to take it down.

Lots of possibilities here, spend some time researching.