The automatic check for updates can be disabled by going to:
View menu | Toad Options | StartUp | choose "Don't automatically check for updates. I will check for updates manually."
Note for silent deployment:
The file that contains the above setting is in the 'Toad.ini' file, which is located at:
C:\Users\<your_user>\AppData\Roaming\Quest Software\Toad for Oracle\1X.xx\User Files\
OR
C:\Users\<your_user>\AppData\Roaming\Quest Software\Toad for Oracle\2X.xx\User Files\
The numbers X.xx will vary depending on the version installed.
For the Subscription version the path will be
C:\Users\<your_user>\AppData\Roaming\Quest Software\Toad for Oracle\Subscription\User Files\
After changing the above setting (and fully exit Toad), you can deploy that 'Toad.ini' file to other user's machines in the same location path.
You can also manually edit the 'Toad.ini' file by opening it in Notepad and changing the value below:
From: CheckForToadUpdates=0 or CheckForToadUpdates=1
To: CheckForToadUpdates=2