Wii U and 3DS demos both impose play limits. For most of these downloads, you can only play them a certain amount of times before they become locked and are inaccessible. Most limits are at around thirty, but some are much lower.
Thankfully, with Switch, play limits are gone. Demos for the likes of Snipperclips, Dragon Quest Heroes I-II, and Puyo Puyo Tetris allow you to load them up as many times as you please. It’s certainly a change that will sit well with Switch owners.