I believe you can send free paid versions, so if it negatively affects those who bought it already, you can have them email you their receipt and send them a free copy.
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I have a question SprintingCucumber do you plan to help somehow the people that paid smaller price and give them access to newer versions or not and we need to pay again?
Yes, actually! I just sent out a promo code email for previous purchasers. It's the first time that I've ever tried to do anything like this, so I hope it reached everyone with the appropriate links all working correctly... I sent it to the email address that Itch has on file for purchases. Essentially it's a $5 coupon for the game, and if people don't want it or don't need it, they can always gift the link to a friend or post it up on a community board. Doesn't bother me at all.