While the software itself is paid, you can find free legitimate content to use with it:
: If you own an older version (like Battery 3), you can upgrade for $99.00 . Native Instruments Battery 4 for Mac Free Download
While there are various sites claiming to offer a "free download" for Battery 4, the only safe and legal way to get it for free is through the provided by Native Instruments. Official Battery 4 Free Demo While the software itself is paid, you can