This file price feature is so bad. Honestly. I do not understand why they have it. First time I read that, I thought that files could be sold individually, like it says on the tin. And a lot of people also do not grasp it. They ask in comments, if they have to pay again for a new version. Extensive study of the faq and community discussions sheds a bit of light on it, but it still is a bad feature. It is more of a one time tier payment. But without subscription. And no possibility to increase, short of paying again.
Some use it, to appear in the free section of games, but still sell for minimum price.
The better (cleaner and flexible) solution to do this is, to have two projects. One free with a public version. The other paid with the premium version. This also has the benefit of appearing in free and in paid, as some people might search for paid games specifically.
If one never intends to change price, that tier pricing might work, but as I said, someone doing so would effectively scam previous customers when raising price of that file. The faq used the nicer wording of "lock out" ;-)
This means that if you change the individually priced file to be more expensive, you may lock out access to that purchase tier from existing buyers. We strongly recommend considering how you intend to price your project in the future before using an individually priced file. Use individually priced files for quick bonus content, not to set the price of your content. Use the minimum price on your project to set the price of your product, as this will allow you to change the price at a later time without affecting ownership.