In the FLEX 500 under Licensing > Registration > Service I see all services as activated. But I can't find the Security WiFi license.
Regarding to the LIC-Gold Security Pack > Secure WiFi license issue, the reason lead to you can't find the Secure WiFi license is that at the present, your USG FLEX 500 still use the UTM Pack in 30-day trial period (expired at 2023-03-04), so your Gold Security Pack is still in Deferred. UTM Pack doesn’t include Secure WiFi license.
Before the Gold Security Pack actives, your USG FLEX 500 still can manage 8 APs. If you want USG FLEX to manage more than 8 APs, need to cancel the trail UTM Pack first. Please let us know your idea and then we can support you.