plugin stopped working

Hello, please tell me why the plugin stopped working and a message about confirming the license code appeared
(…This is the License Activation Panel. After purchasing extension from WP Swings you will get the purchase code of this extension. Please verify your purchase below so that you can use feature of this plugin...)?
the license has not yet expired. when inserting the key it reports that “Reached maximum activation. License key already in use on…..”