Amazon allows authorizations for 3rd party developers to be valid for only one year. You will get several email notifications from Amazon when you have authorizations that will be expired in a couple of weeks. In this case, you can go to Seller Central and simply renewing your authorizations for 3rd party developers.
For a video tutorial on the entire process, please watch this video:
Step by Step Guide
1. Navigate to Settings > User Permissions.
2. Go to Visit Manage Your Apps.
3. You can Renew/Disable/Enable for any 3rd party developer or app that are integrated with your Amazon Account.