When you say a more expensive "upgrade" would be forced on them, do you mean just the full price as if it were a new purchase? Or are there threee levels of product pricing:
1. new purchase/full install
2. Upgrade purchase (but what if they already haev the latest version?)
3. renewal pricing
Admittedly I don't know a lot about how this works as I haven't had occasion yet to be concerned. Say my customer has version 11 of SEP yet they for some reason decline to make a purchase until after 90 days beyond expiry - what are they buying at that point? Version 12? or just version 11 again at full "new install" price?