Does my licensed plugin expire?
Yoast premium plugins for WordPress are yours to keep and use for as long as you want. With each plugin purchase, we include a renewable license for upgrades and access to our premium support team. The license is valid for one year from the purchase date and is not automatically renewed. At the end of the year, we will send reminders that your license is about to expire. You can either renew the license to continue receiving updates and support or let the license expire.
We want to assure you that the plugin will work regardless of the license activation status. How long it will continue to run for you, without a license and updates, will be determined by what other factors in your site change including core WordPress updates and your other plugins.