Old versions are kept until the end of the internet: Basecamp's 2004 version, unsold since 2010, still makes millions in profit.

Creator of Ruby on Rails, CTO of 37signals

So, for Basecamp, we kept those old versions. The version we launched in 2004, we stopped selling in 2010. 16 years ago. We still have customers on it. As an individual business, it's still making millions of dollars.