I think it's a matter of perspective. We do this with enterprise software, except we don't call it a "time bomb".
"We've deployed your installation with a provisional, expiring license. We'll issue your permanent license once you've confirmed the software is installed and configured to your liking."
Then when they send the check, we send the license. It's never been a problem for any of the parties because we've always been very up front about how the process works. No surprises.
"We've deployed your installation with a provisional, expiring license. We'll issue your permanent license once you've confirmed the software is installed and configured to your liking."
Then when they send the check, we send the license. It's never been a problem for any of the parties because we've always been very up front about how the process works. No surprises.