If you sell a premium WordPress theme that you intend to maintain and update for a long time, it's reasonable, and often a good idea, to use a limited time, renewable, license system. Users would pay yearly for continued access to support and updates. It helps you maintain a sustained income while you continue to work on the theme.
But then the question arises of whether or not to make those renewals automatic. It certainly makes it easier for the user to not have to worry about renewing, but automatic billing comes with its own issues as well. The author of the article below presents his experience and some considerations to help you make this decision for your own theme.
When we first started selling WordPress themes in 2009 it was industry best-practice to offer “lifetime” support and updates. At the time everyone selling WordPress themes was offering unlimited support requests and updates and we were happy to do the same.
All was well for a couple of years, but eventually questions about sustainability started: if you purchased a WordPress theme once for $60, is it a fair deal to both parties to offer unlimited support requests and significant updates for years to come? As popular themes started receiving huge updates years after their original release, questions about sustainability started arising.
Read the full article: Should Premium Themes Automatically Renew Licenses? Data from Thousands of Theme Sales