There are two separate messages, and each should be presented only once, assuming you have updated to the final update of Office 2011 version 14.7.7
When you launch an Office 2011 app, you might see a yellow band under the Ribbon. I don't remember exactly what it says because it displayed only once for me and now I don't see it. This is a notice from Microsoft.
Apple displays a dialog when you open ANY 32-bit application (or even a printer driver) in a current version of Mac OS cautioning you that at some point 32-bit applications will no longer be supported. Again, once you have dismissed that dialog for a given
application it should not display again for that application, unless you are using Mojave, where I think the reminders display regardless because at some point your apps will stop working.
To the best of my knowledge there is no way to turn those reminders off.
Microsoft offers a variety of licensing types both perpetual (primarily for IT shops) and subscriptions. Home and Student is the only one that does not include Outlook.
Microsoft Offers suggestions on which version is right for you, depending on your needs.
Choose the option that's right for you
For home
For business
For education
In addition to the above, Microsoft offers a completely free, reduced feature version of Microsoft Office on line with
OneDrive. This version competes against other free lightweight Office suites such as LibreOffice and Google Docs. There is also a free, lightweight on-line version of
Microsoft Outlook. Microsoft OneNote is available for free from the Apple app store.
In general, if you want the full featured set of Word, PowerPoint and Excel I advise getting a subscription. Although Microsoft sells perpetual license versions, they're made primarily for IT shops. If your hard drive dies or you wipe it clean, or you buy
a new Mac, you'll probably have to purchase a whole new perpetual license in order to keep using the suite. If you buy a subscription you have full control over your installs (up to 6 of them). A subscription makes you keep your hardware and operating system
up to date in the sense that after 6 years (if it's brand new today) your hardware and OS probably won't be current enough to install updates.