I have the paid version.
I generally have it set to keep my MacBook Pro at 80% since it is always plugged in. I use the “sailing” mode. I think it helps, but as the author of the tool explains, it’s hard to know for sure.
I do not recommend paying for the software. The paid version will turn itself off every 30 days unless you let it phone home to verify that it’s still authorized. I’ve written/sold software before, so I get the concern about piracy, but this is going too far.
This means you can’t run it on an air-gapped machine. It also means the developer is collecting data tied to your name, address, credit card, IP, and computer usage every month and you can’t opt out. Most distressingly, it means that someday when the author loses interest in the software (or doesn’t renew his domain name, or has a heart attack, or sells it to some unscrupulous corp) the software you paid for will stop working.
Merlin is amazing. I heard birds outside my new apartment and thought of them as nice background noise. Within days of installing Merlin, I could tell sparrows, cardinals and robins apart without seeing them. Whenever I heard a new bird, I’d grab my phone and open Merlin.
One day it sounded like a robin and a cardinal were having and argument while both simultaneously having a stroke. Merlin figured out it was a catbird, a relative of the mockingbird that learns the songs of other birds then strings pieces of them together in a disorganized song to impress the ladies. Basically, the male catbird who can sing the weirdest songs using the most species signals that he has “been around” for enough seasons to learn all those songs and therefore must have good genes the females want to pass on. It’s mind blowing to learn all this about things that are going on outside your window.