Thank you for contacting WPML Support. Please make sure your current site URL and registered site URL are the same e.g. with www or without www.
Could you please follow the below steps and let me know how it goes?
1. Go to Plugins >> Add new > Commercial tab and click the ‘Unregister WPML from this site’ link if that link exists.
2. Then please click the ‘Register WPML’ link.
3. Click the ‘Get a key for this site’ link.
4. It will generate the Key for your site.
5. Copy the key and paste it back to the input box and press the Register button.
If still an issue persists, please delete the existing key and create a new one by following below steps:
1. Please login to your WPML account >> Go to the Sites page.
2. Delete the existing site key.
3. Create a new subscription key for your site.
4. Visit the Site Dashboard and go to Plugins >> Add New >> Commercial tab.
5. Click on the “Unregister WPML from this site” button.
6. Register with the new site key and refresh the page.