The free plan doesn't expire!
A free plan is always FREE!
As part of the Free plan, we give back to the community and you can host up to 10GB of files and use up to 20GB of Bandwidth each month.
You can use the free plan as long as you want and you won't be charged.
If you get to the point that you need more storage or bandwidth you will have the option to upgrade to the next plan.
Here are instructions on how to upgrade