I have a setting where there is an online shop that sells magic script, which sent via email. The magic in this world is activated via a runic script - similar to a program code.
The problem is, I don't know how this shop could deliver the rune script (magic "scroll") safely without anyone be able to copy the rune script after the delivery. Different from program, the runic script is not compiled, so everyone could see the source "code". It can be photographed, or redrawn, and that's the issue.
Like a program code, the effect of various scripts is different. Even a fireball spell can be designed with different colors, or even a rainbow fireball! So, the issue with copyright here - I don't want my rainbow colored fireball script to be freely used, they must buy it from my shop. It is very hard to write the correct script to include each color and not make it too green or blue.
The script can be deciphered by an expert runologist, but the general idea of what the script does can be inferred immediately after seeing it. It's like reading a kanji for "Fire", but complicated with the kanji for 7 colors.
So, the setting is like in our 21st century modern world. Magic already exists from the beginning, but only few (I'm thinking less than 100 in each country) actually know how it works. The numbers greatly decline through the time because less people believe it, and spend time to actually understand it. Thus, the magic communities developed an online shop for their community to use - ordinary people would just shrug off them as nonsense website.
So, how to protect the magic script from piracy?
Note: Anyone can activate the magic script without needing magical power. It's like flipping a light switch. The rune need to be drawn using magical ink, but it is not rare, in fact it's very, very common and easy to acquire in the magic communities.
The license ideally works only on the buyer, and not anyone else, even someone that can produce the exact image of the magic script. The license is transferable, either independently from the author or requiring the author to send a new script or altering something else, either is fine. I prefer a non-shareable method for a single magic script (even for family) to prevent someone else able to fake the authorization, but I'm not too tight on this specification.
Related How do sorcerers attempt to prevent common people, or other sorcerers, from duplicating their spell scrolls?, but this is different since this takes place in modern world (and thus worsen the problem of piracy, because it can be posted in forum, sent via chat clients, and such), and this is not a one-use only transaction - the buyer should be able to use the said scripts, but not his friend that receives the photo of the script.