If you have the free version and download the free version again it's obviously free.. if you had the PRO version and less than a year has passed, the upgrade is still free, if you had the PRO version and an entire year has passed since your purchase, you have to pay for the upgrade (this way you renew your license)
For the PRO renewal you have to pay €19.90, for the PRO Lite only €7.90
If you had the free version and want to purchase PRO or PRO Lite versions, they respectively cost €29.90 and €9.90
More info
here
And on your
user account page (if you are a registered PRO user)