[tlercher]

They can.

[MAS = Mac App Store, nMAS = non-Mac App Store]

The only (okay two) way that is impossible to do is: MAS ➜ MAS (and nMAS ➜ MAS)

but:

non-MAS ➜ non-MAS: via serial in the store MAS ➜ non-MAS: Receipt Validation (https://developer.apple.com/library/mac/releasenotes/General...)

the last one is rarely used by Developers… 1Password is one, that allows you to buy it in the MAS, and use at least their Beta-Builds.

That many developers use the MAS as an excuse, for not providing any upgrade paths at all… is a very silly solution to a problem that many Developers/Companys face (to make permanent profit) at the cost of customer satisfaction.

[cjensen]

A paid upgrade for store MAS ➜ non-MAS is forbidden by Apple. Omni already tried that [1].

[1] https://www.omnigroup.com/blog/omnikeymaster-upgrade-pricing...