Does whitelist work after content filter demo expires?

On the 4.2 firmware, there is now an option to filter https traffic. We have some users that have there own internet content filter proxy server that routes traffic through port 6502. Therefore they don't need a content filter subscription because they have there own content filter. We want to force users to use the proxy and so we block port 80 and 443, so if the proxy setting is disabled on their computer, they can't get unfiltered internet. We also use the trusted web sites whitelist to add sites that can go out direct, like windows updates and office, that do not follow the proxy. This works as long as the content filter demo is active, but will it work once it expires? We know it does not work to setup on a usg router after the content filter demo has expired