A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
As Palcouk says, you may use the trial version for 30 days, then either pay for a subscription or stop using PowerPoint. I'm pretty sure that you'll have access to any files you've saved for quite a while longer, but if you have any that are important to you, I would certainly log into your OneDrive account using a computer and download them the computer's hard drive or possibly email them to yourself.