How to know when certificate will be invalid in AP

[eigrpy]

HI, I would like to buy ap 3502 for practice. I am not sure if how long it can be used because the another ap 1142 cannot join wlc due to its certificate failed. The info of 3502 EOS etc are listed below. Any experts can tell when the certificate will be invalid? Thank you

https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3500-series/eos-eol-notice-c51-734303.html

[Grendizer · Accepted solution]

Check the link below:
https://community.cisco.com/t5/wireless-mobility-documents/lightweight-ap-fail-to-create-capwap-lwapp-connection-due-to/ta-p/3155111

check the section:
How to Identify Certificate Expiration date
(via CLI or Serial number or Python Script or WLCCA)