Say you are only working in one presentation. You need it to be the best and therefore you came to Slidebean, but it's only one.
Unlocking a presentation is a single purchase to enable the main functions that are unavailable during free Trial: Full screen, Share, and Export. You can also continue to edit and update that presentation without time limitations.
You will find this option after trying to take any of the locked actions mentioned before: present in full screen, share, and export. A pop up will show on your screen to let you know your purchase options.