How do I find my captivate 9 license no? I didn't register it.

If it is a perpetual license, it should have been activated, or you wouldn't have been able to use that license. Was that the case?

If it is a subscription license, you don't need a license number, your Adobe ID used when hiring that license is all you need.

You cannot display it from within Captivate. However, if you have a regular consumer license you can log into your account on Adobe.com and view all your licensed products under Manage My Account.