You are no longer able to edit images because you have reached your monthly quota.
Please note that every single image edit requires our servers to download, process, and re-upload the image. The enormous amount of bandwidth and processing power needed to do this results in large monthly server bills. For this reason, billing is done by the image - with the free plan limited to 50 edits per month.
In order to get more edits per month, you need to click on Plans and Pricing at the top right corner of the app and select a new plan. The limit increase will take place immediately when upgrading. If you do not upgrade plans, you would have to wait until the 1st day of the next month for your image quota to be reset.