He’s talked about it on the podcast he was on. So many users would buy this, run it once, then save a few gigs and be done. So a subscription didn’t make a ton of sense.

After all how many perfect duplicate files do you probably create a month accidentally?

There’s a subscription or buy forever option for people who think that would actually be quite useful to them. But for a ton of people a one time IAP that gives them a limited amount of time to use the program really does make a lot of sense.

And you can always rerun it for free to see if you have enough stuff worth paying for again.

For me the value in a dedup app like this isn't as much the space savings, since I just don't generate huge amounts, but it's the lack of duplicated files, some of which or all in aggregate may be large. There are some weird scenarios where this occurs, usually due to having to reconcile a hard drive recovery with another location for the files, or a messy download directory with an organized destination.

For example, I discovered my time machine backup kicked out the oldest versions of files I didn't know it had a record of and thought I'd long since lost, but it destroyed the names of the directories and obfuscated the contents somewhat. Thousands of numerically named directories, some of which have files I may want to hang onto, but don't know whether I already have them or not, or where they are since it's completely unstructured. Likewise, many of them may just have one of the same build system text file I can obvs toss away.

am I really that old that I remember this being the default for most of the software about 10 years ago? Are people already that used to the subscription trap that they think this is a new model ?

I grew up with shareware in the 90s that often adopted a similar model (though having to send $10 in the mail and wait a couple weeks for a code or a disk to come back was a bit of a grind!) but yes, it's refreshing in the current era where developers will even attempt to charge $10 a week for a basic coloring in app on the iPad..

I also really like this pricing model.

I wish it were more obvious how to do it with other software. Often there's a learning curve in the way before you can see the value.

it’s very refreshing compared to those “free trials” you have to remember to cancel (pro tip: use virtual credit cards which you can lock for those so if you forget to cancel the charges are blocked)

however has anyone been able to find out from the website how much the license actually costs?

Doesn’t the Mac App Store listing list the IAP SKUs like it does on iOS?

It does. It's reasonably clear for this app but I wish they made it clearer for other apps where the IAP SKUs often have meaningless descriptions.