Does my plugin expire?
If you’ve downloaded and installed our Yoast premium plugins for WordPress, they are yours to keep and use for as long as you want. With each plugin purchase, we include a renewable subscription for upgrades, downloads, and access to our premium support team.
This is an annual subscription and must be renewed to gain plugin updates, downloads, and support.
However, we want to assure you that all features and functionality of the plugin will work regardless of the subscription status with the exception of the morphology functionality (word forms). This feature requires an active subscription to work.
Though, how long it will continue to run for you, without a subscription and updates, will be determined by what other factors in your site change including core WordPress updates and your other plugins.