What is the Expiry date in the About page?

Can anyone tell me what it is that expires, in this screenshot, on December 1st and whether it is something I need to

a. worry about

b. do something about

This is my error. The 6.0.2 build will stop working on that date. Thanks for noticing my failure to remove the expiration date. Nothing to worry about. I’ll resolve the problem with another release before 6.0.2 expires.