Sometimes we can't reach our clients due to various reasons, such as an expired domain, no longer working there, vacation, etc. So we usually try to find someone in their company that can renew the service by checking old emails, company website, google, etc. This usually works, but for personal accounts (ie with a gmail address) it doesn't.
We're thinking of flipping the switch to enable automatic payments, but we like how our clients can truly evaluate if they still need the service before renewing. We also anticipate some problems such as a higher chargeback rate.
The question we have is how do you, at your company, reach clients that don't have valid contact info anymore? Do you go through a similar process?
At some point, the license will expire and the software will stop working. 90% of the time, this will result in an emergency call to our tech support, who will issue them a temporary (2 week, I believe) license and get the updated contact for who to reach to talk about a real renewal.
However, our customers are medium-to-large corporations and our software is system-critical for them. I'm not sure if this approach would be reasonable if your customers are normal human beings.