People who download something for free do not own your project, so when a price is added they will not be able to download it anymore. If they paid any amount for it though they will own it. So, for example, if they donated a dollar, but then you set a minimum price of the project of 5 dollars, they will “own” it and have access
There are a few exceptions to what I described above:
- If you host a sale with a 100% off & claiming enabled, then people who claim it during the promotion will permanently own it
- If you set individually priced files, then those files verify look at the original purchase price. So a 1 dollar donation would not unlock a 5 dollar file.
Hope that helps