[Buttons840]

Maybe. One of the primary advantages of offline software is that it can be used offline. If you're going to require people to connect to your server you might as well make it a web app.

To be fair, it's not really all or nothing like that, but remember that offline software is already a niche market. Is it better to go half-way into a niche market, or all the way? In other words, your users likely chose your software over the dozens of online offerings because it is an offline app, and then the very first thing you do is make them connect to your server.

Although, I don't see any downsides of doing server-side verification if there is a network connection available, it would be nice if offline software could work on a computer that was offline.

I'm working on a side-project that I may sell as offline software. One of my marketing claims will be that the users own the software forever. They wont experience a "UI upgrade" that makes things worse, and if I go out of business their software will still work for decades or longer. I cannot honestly make that claim if I require server-side verification. I'm betting that my niche users will care about this; if not I have no product because there are dozens of online competitors.