If your subscription has expired or did not auto-renew, you can still use the plugin on your site for as long as you like but you can no longer access the file for download or receive support or updates for the plugin.
Many of our customers download their plugin(s) before the expiration of their subscription to keep a copy on file, if they know they cannot or will not renew. Our support team will not offer the download files if your subscription is expired.
If you are having trouble with the plugin, go to the plugin's product page and check the Changelog to see if an update may help address the issue. When a plugin is not working, updating should always be the first step when troubleshooting.