So you have myolddomain.com and you are moving to mynewdomain.com, do you need to renew the security certificate for the domain myolddomain.com if you are just going to be redirecting it to mynewdomain.com. The answer is probably yes, not necessarily for search engines but users may get a browser error on the redirect.

John Mueller of Google responded to this question:

He said browsers need it, search engines probably don’t but since security certificates are free these days, just do it:

For how long should you keep that live? John said for at least two crawls, which can mean more than a year?

The topic of how long do you keep redirects up is something we covered numerous times. In general, keep them up for at least a year but in practice, keep it up as long as you can.

Forum discussion at Twitter.