Hi!

So I'm making a ttrpg on here and it's a work in progress, but I want to make some money with each update. The problem being, I don't want to make it super expensive to upgrade. Just a little bit of extra cash. So I was wondering if it was possible to set up discount codes, kind of like the free key codes. The idea would be that when I upload a new version, I'd upload the discount code to the previous 2 versions of the game for the newest update. It'd kind of be like a subscription service of sorts. But I don't know how and haven't found anything on the forums that would pertain to that kind of thing. Is that possible? And if so how?

On a side note, I was also wondering if there was a way to make content creator codes like they do for world of warships or whatever. My goal would be that I could generate a code for others that, when someone uses the code while buying the game, it would give some % of the proceeds to them. I already asked about this on another post, but it didn't get a ton of views and the replies weren't what I was looking for. 

If anyone knows how to generate codes like these (or something similar), that'd be great. Thanks in advance!