User Configuration > Administrative Templates > Microsoft Outlook 2016 > Outlook Options > Preferences > Calendar Options > Recurring item configuration
User
HKCU\software\policies\microsoft\office\16.0\outlook\preferences
This policy setting allows you to disable the "No end date" option for the recurrence range in appointments, meetings, and tasks. If you enable this policy setting, the “No end date” option is disabled, and the “End after” recurrence setting is selected and set to “10 occurrences” by default. You can change this default setting by configuring the “Specify total number of days in a recurring meeting or appointment” policy setting. If you disable or do not configure this policy setting, the “No end date” option is enabled and is the default setting for recurring meetings, appointments, and tasks.