If you’re unable to update the plugin via your WordPress Plugins page then there could be a few reasons why:
Your license key isn’t activated on the website
If your license key isn’t successfully activated on your website then you won’t be able to install updates via your WordPress Plugins page. Follow these directions to activate your license key on your website. If your license key appears to already be activated on your website then try deactivating and reactivating it on the License page. You can check within your Account which website(s) your license key is activated on.
The license key you’re trying to activate is invalid
Make sure you’re not accidentally trying to activate your purchase key or invoice key. Your License key is listed within your Account and also emailed to you when you first purchase the plugin.
You’ve exceeded the number of sites that your license can be activated on
If you have a Personal (1 site) license then check to make sure it isn’t already activated on another domain, such as a staging or test/development site. If you have a Business (5 site) license then it’s possible that you have already activated the license on 5 other domains. You can check the sites that a license is activated on in your Account.
Your license key has expired
If your license key has expired then you are no longer eligible to receive plugin updates. You can renew your license key by clicking on the ‘Renew’ link next to your license in your Account.