If one upgrades all licenses of Progress 9 version to OE 10 – under maintenance contract (translates to getting OE 10 at no charge – but pay yearly maintenance).
Is there any time limit that users have to be converted to OE 10 and stop using version 9. How long are we allowed to use 9, after upgrading to OE 10.
This is a question that you should clarify with your Progress sales rep.
As we all know, it is generally not possible to install the new license and stop using the old on the day the new one gets produced, so there is obviously a window where the new license has been received, but the old one is still in use. How long this window should be is something to discuss with your sales rep.
In practical terms, of course, no one is likely to be looking over your shoulder. The key in such situations is typically intent. I.e., if you install the OE10 license on a separate box and start running a different application with it, that would be considered a bad thing even on the first day. If the OE10 license is installed on a new box which is going to become the production box, but you run into some snags and it takes a while to sort out being ready to switch, I can't imagine anyone squawking, even if you were audited at that stage.