I’m not sure, but I think maybe you are trying to enter your older license into TaskPaper 3? TaskPaper 3 requires an upgraded license. You can download TaskPaper 2 here:
I no longer sell licenses or support these older versions of TaskPaper. I provide them here for curiosity sake and to allow people to run TaskPaper on older versions of OS X.
TaskPaper 1.0
TaskPaper 2.3.2 Important, won’t work on macOS 10.12 and beyond
Here’s a license key that will work for both versions. Please note that over time the license key system has become brittle. Copy the text exactly! Avoid extra spaces. Version 1.0 doesn’t allow Command-V to paste… instead paste by right clicki…
Also if you want to upgrade your license to TaskPaper 3 you here are instructions:
Yes, TaskPaper 3 is a paid upgrade.
And in fact since the Mac App Store doesn’t allow upgrades TaskPaper 3 is just a new app with no special upgrade process pricing. If you have an old TaskPaper license and want a discount please email me (jesse@hogbaysoftware.com ) your license or Mac App Store order info and I’ll give you a 50% Off coupon.