What happens to a cisco device if its smart license expires

[ahmad.rz]

Hi there.

Recently I upgraded a Cisco catalyst switch with the IOS version 16.12, following which smart licensing was enabled. The question is what happens if I do not want to activate it and what happens to the switch and its functionality once its expiration period is over ?

[Kasun Bandara]

there is a many things you need to consider about cisco smart license. check below overview

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/smart-licensing/qsg/b_Smart_Licensing_QuickStart/b_Smart_Licensing_QuickStart_chapter_00.html

[ahmad.rz]

Follow the link:

The evaluation period applies to the whole device rather than to invidual features or entitlements. When the evaluation period expires for a device, it cannot be reset. After the 90 days time period, these licenses move to the Expired or EVAL EXPIRED state.

Okay. But What limitations apply when the state changes to EVAL EXPIRED ?

And I still don't understand what is going to happen really.

[balaji.bandi]

Depends on the device what License it was applied.

if the device acting only basic - like essential ( that is perpetual, nothing going to happend to device)

if more than that advantage License, the feature still going to work, but compliance issue to get right License to use.

[Leo Laohoo]

Depends on what license has been enabled. 
If only basic Layer 2 license, nothing will happen when the Smart License expires, HOWEVER, I more concerned with memory leak caused by Smart License. 

Since 16.12.7 is going to be the last release (3650/3850) and there are many memory leak attributed to Smart (Licensing) Agent, keyman, RUM Report, etc., I'd really stay away from using 16.9.X to 16.12.X.  Downgrade to the latest 16.6.X if possible.

Smart License is not as crack up as Cisco claims and provides zero advantage to the customer.

[ahmad.rz]

Thank you! Is it okay if I downgrade IOS to the version where smart license isn't mandatory, but smart license is still operating ?

[Leo Laohoo]

If this is a router, downgrade to 16.9.X and earlier (16.3.X or 16.6.X). 

If this is a switch, downgrade to 16.6.X or 16.3.X or 3.X.X.  

Nothing wrong with downgrade as long as the switch can support it.