If you no longer want to backup a certain computer but you want to keep its data to restore from it later, then archiving the computer is the best option for you.
Archiving a computer will remove it from your added computers while keeping the backed up files (the used space won’t be reduced). It is usually used for computers that you don’t wish to use anymore, also to save a spot for a new computer on your account (since you are allowed to add only one computer (for Home users) and three computers\user (for Business users)) while keeping the files of the archived computer available for later restore.
If you wish to temporarily stop backing up that computer, instead of archiving that computer. Suspending a computer is like pausing the backup on this computer from the server side, this doesn’t remove the computer form your “My Computers” page on the dashboard, instead, it just tells the desktop client to suspend the backup from this target computer and wait for a resume request.
Finally, Once you archive any machine, you will not be able to activate it or continue using this backup again.