According to Ipernity

"Overlimit upload for this month

You're over the limit of your monthly upload capacity.

Even though you haven't reached your upload limit, your uploads lasted 50m 53s on our servers (the max duration is 3h per month.)

In that case, you are allowed to complete your uploads during off peak activity hours."

What is strange is that as a free user I have not uploaded a single file. Apparently because I uploaded files with my pro account before it expired yesterday I am not allowed to upload files as a free user.

Kind of strange attitude and makes me think about whether I want to renew my pro account.