Kingdom Come: Deliverance deliberately doesn't allow you to save the game whenever you feel like it, insisting that you either buy or brew a bottle of something called Saviour Schnapps first. It's a heady beverage that saves your game even as it gets you drunk, and by the sounds of things it doesn't seem too easy a beverage to come by. While the game does autosave on occasion, it doesn't do so when you exit out, so it's understandable that one of the very first Kingdom Come mods is one that does away with this punishing save restriction.
EddieShoe and Biosmanager's Unlimited Saving does exactly what you would expect, by eliminating the need to guzzle down a bottle of tasty Schnapps before you're allowed to save.
There is a potential wrinkle with the mod, however. There have been reports that, with the mod installed, people have been unable to save at all after their 300th save. Co-creator EddieShoe has posted a workaround, which I've pasted below, but it's something to bear in mind.
"Someone has reported that the game won't let you save after you've got 300 saves. Take backups of all your saves, remove all saves except your latest one. Now go in-game and load that save, delete it from the load menu and then save. It should be labeled as 'Save 1' now. I'm not sure if this issue even exists as I've only seen one report of it, but it's worth trying if you run into it."
The lack of quicksave was one the criticisms in Edwin's Kingdom Come review. He felt that not supporting the feature was annoying partly "because the game is somewhat prone to crashing at the moment, and partly because Kingdom Come’s melee combat is as tough as horseshoes."