I am running Aalto from a Windows 10 (x64) host, inside Ableton 9.1 (32bit VST).
For some reason the license seems to reset constantly (see attached gif).
Sorry you're having trouble. The GIF didn't make it—you can email it to me at support if you'd like.
If pasting the license goes OK, but the plugin is not licensed the next time you open it, there was probably an issue with writing to the disk. Maybe you are running as some account that does not have permission to write to the license directory? You can try copying the license to the directory by hand to find out.
On Windows, license files are in C:/AppData/Roaming/Madrona Labs/Licenses. When the plugin starts up it looks for a file with its name “Aalto.txt” “Kaivo.txt” etc. in this location. The file is a plain text file that contains the license key. So, you can try looking there to see if there is an old license.
Unfortunately these AppData folders are now hidden by default in Windows 10. To see them, try this tip: http://www.pcworld.com/article/2690709/whats-in-the-hidden-windows-appdata-folder-and-how-to-find-it-if-you-need-it.html
I run Aalto in the same environment and never had this problem. The Aalto.txt in %APPDATA%/Madrona Labs/Licenses looks legit and there is no diff to the license optained online.
Edit: found the error
As it looks this only happens when starting the Ableton with Admin rights. I sometimes have to do it because another Plugin cannot load if I start ableton normally.
Thanks for following up with the solution. I'll look into adding better error messages or otherwise improving the experience when this situation comes up.