You pay for all the materials and the work put into making the piece and it’s yours but your don’t ‘own’ the copyright of the pattern any more than you own the copyright of a book you purchased - you just bought a copy to read / use. The pattern itself is of course different to a the piece made from the pattern. The nature of cross-stitching as a hand-crafted product means the economics rarely make this an issue and mass production refers to mechanized duplication. You can also make more pieces from the same pattern but what you can’t do is ‘mass produce’ them. That means you can sell it, donate it, give it away or whatever you want.
Some people claim that you are only allowed to reproduce it once and if they impose that restriction as part of the contract of sale that you are made aware of before purchase then it is true but most of the time the piece is yours and you can so what you want with it. When you purchase a pattern, part of what you are paying for is the right to reproduce that image - that is the whole purpose of a pattern after all. It’s not really any different to taking a photo of it, it just takes a lot longer. Well, patterns and charts are all about the image - you are taking a picture, creating a pattern to serve as the instructions to reproduce that and then using that pattern to reproduce the likeness of that image in another medium. How does all this relate to cross-stitching? It’s also deemed to be more egregious and so is often pursued more vigorously by those protecting their copyright. Obviously, if you have a web-store and are advertising things for sale that you do not have permission to use then it’s much easier to find out about it than if you have just printed off a picture at home and put it on your wall. If you steal something from a store, it doesn’t absolve you of guilt if you give it away instead of selling it. Some people think that it only matters if you intend to make money from the image but this doesn’t really change whether something is legal or not. Look for Creative Commons CC0 licensed images which can be used for commercial use.
There are many websites that make free images available. Sometimes these are limited to academic or editorial use only but others allow commercial use where you could make products for resale based on those images. Some people want their images to be used and generously make them available for other people to use by placing them in the public domain.
There is an exception which is if you are paid to do it (maybe as part of your job) and the terms of the contract state that you assign ownership and copyright to the person who is paying you to take it. It comes down to copyright - if you create the picture then you own it and can do what you want with it, reproduce it, sell it, give it away, whatever you want.
If you don’t know that you are specifically allowed to use an image, then you probably aren’t. There’s a quick and easy default answer: no. Whether you make a photocopy of a picture, take a photo of it or make a pattern and produce a piece from it, you are reproducing the image in one way or another.
Ok, so how about if you leave it there but just make a copy? They’re not losing anything then are they? Well, yes - people pay for rarity and exclusivity and if you are just making copies for free then it devalues the piece and why would anyone pay for something if it was ok to get it for free? What Images Can I Use? The web version may offer little protection to prevent it, but to suggest that made it “OK” would be akin to claiming that a store assistant who left the door open and took a break gave you permission to steal. The fact that the image is for sale in a store, gallery or on a webpage doesn’t make it any more legal to take without permission. That is the thing that an artist or photographer worked to produce and it’s not just yours to take. But while you would be stealing a frame and the print, the most valuable part of the picture is very often the image itself. Of course you wouldn’t try to steal it and most people recognize that this would clearly be theft. Imagine instead it’s a framed print in a Crate and Barrel store. You’re probably thinking about something on a webpage, don’t. You see an amazing picture and think “wow, that would look fantastic on my wall !“.