Thanks very much Wiki
Most probably you are using EVAL and is valid for a short time. With Eval expiry, it will continue to function with existing signatures. But after expiry it will not get new signature updates. You will need to purchase a license to use it in production or install a new TMG server if this is for demo or for testing purpose. By default, TMG provides and enables an evaluation license for TMG WPS that expires 120 days after installing TMG; not 120 days after you enable EMP or URLF. Hence, one way you can do (take a chance) to enable WPS and see what is the number of days its reflecting there.
CAUTION: Before doing, please take a backup of TMG, firewall polices etc, just for safe.
Also do one thing, just run an installation wizard, without un-installing the current installation and observe either it will be converted to RTM!
Hope it may help you!
Yes, I also thanks for your healthy response! The above writings help you, I hope so.