You don’t have to renew your membership. However, your themes and plugins won’t receive any further updates after the first year.
We strongly recommend keeping WordPress themes and plugins up to date. You can renew at a 30% discount on the standard price.
If you will be using Themify’s themes and/or plugins for several years, it’s the best value to opt for their Lifetime Club membership. This gives you all future updates and all new themes and plugins that Themify creates.