SSH service on Cisco device - need to restart after config changes?

I have a Cisco device and am trying to make changes in a pseudo-prod environment. Working on temporarily removing the session limit for SSH to the device. Have a VTY line configured for SSH

line vty 2 4 session-limit 2 logging synchronous transport input ssh transport output ssh 

When I remove the session limit line (no session-limit 2), it doesn't seem to allow any more sessions. Do I need to save the running config and reboot the device? I know that typically changes to SSH config usually require a restart of the service but wasn't sure if this qualified as such.

What I am trying to accomplish: I am working on scanning this device via Nessus and running into an issue where the scanner is able to authenticate via ssh but with intermittent failures. I believe the issue to be related to session limit. The reason I believe this is because I have another Cisco device that I'm able to scan without issue whose VTY lines are configured the same but without the session-limit line.

Cisco device I am able to scan without issue:

line vty 0 1 logging synchronous transport input ssh transport output ssh 

Edit: I have edited my question to include what I am trying to accomplish and more information on what I have had success with.