For my comment below, I am going to type theme but I mean plugins as well.

What's to stop me from geting a theme, claiming it doesn't fit/don't like it/etc... then requesting a refund, getting refund then 3 hours later using that theme?

Technically speaking nothing.

I think most people get refunds because they THINK the theme does not fit.
I know, that you as the theme author can have a demo of the theme, still not the same, since I have different plugins as your demo.

Refunding on a theme is like the author of this post getting underwear and then going back to store to get a refund.

Underwears, thongs, bras, speedos, bikinis and so forth can't be returned for health issues.