There are plans to solve these two issues (automatic updates + trial to full migration) at the same time. The only problem is that to enable this we need some kind of DRM mechanism. We have plans to:

1. Offer a trial version that can be converted into a "full version", where inserting a license key enables the full version/save operation: This solves the issue to migrate/copy sprites from the trial version to the full version Handle migration of sprites from trial version to full version #533
2. Add automatic updates if the license is still valid.
3. The new "full version" must work as the current DRM-free version, no need to have an internet connection to work, nor any license check while working. It must have the option to insert a license key to access the automatic updates feature. We think that a lot of users will want to continue using the facility of the DRM-free version which doesn't require a license key (the only drawback, is that automatic updates are not possible with this version, only through Steam, which is the one that handles the DRM now).
4. Differentiate between licence types, which means that educational licenses will have a different license validation scheme than the end user license. Basically, educational licenses will be checked more often than the end user license, which is going to be validated only when an automatic update is triggered.

In this way the workflow for new users will be:

1. Download the demo version
2. Purchase Aseprite
3. Get a key (just like getting the Steam key from Humble Bundle) and insert the key in the demo version
4. Now the user has the full version of Aseprite that supports automatic updates

The good part is that there is no need to re-install/re-download a new installer, and new updates should be downloaded automatically. Anyway in the step 3 the users will have access to the "full version" anyway. So the current workflow will be available.