Does my 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 subscription for upgrades and access to our premium support team.
This is an annual subscription and must be renewed to gain contained support and plugin updates.
However, we want to assure you that the plugin will work regardless of the subscription status.
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.