Yes, pretty much usability and smooth migration. Ideally, when the user “upgrade” from the Lite version to the Full version, all their diagrams should continue working and get all features available only in the Full version.
There are a few challenges that I can think of.
Linking the two applications. From platform point of view, Lite and Full are to separate applications. Thus they have their own ID, Lifecycle, License Status, etc. This can potentially be solved within the Apps. If it is made aware to the Lite App about the Full App Licence status, then it can switch to a Full mode and load JS for the Full App.
Sharing data. Once the two Apps are linked, we need a way to share the data between them. Ideally, we do not want the backend to be involved in this sharing. Some Apps like ours does not require a back-end server to run its core functionalities.