You've got enough followers that will pay any price for the product, to "upgrade" the same program to a different platform, etc. and you figure you have earned it with all of the code you've written. Maybe. But charge AFTER you work out all of the numerous flaws. Also have a loyalty program for customers that have been with you for more than 30 years... It's kind of like a Senior benefit for Senior patrons who have supported and done a lot of word-of-mouth advertising over the DECADES. It all evens out. Believe me.