This thread addressed the OP's concern without fully straightening out his misuse of language, which may be a factor in your confusion. The OP was asking about common law (unregistered) trademarks and wanted to know when they "expired."
What we answered about was "abandonment". Properly speaking, trademarks do not "expire." Like old generals, they never die -- but they can and do fade away -- that is, they can be abandoned.
Just as a person may be presumed dead after going missing for so many years, a trademark is presumed to be abandoned when not in use for a sufficient period of time. For Federally registered marks, three years is the magic number after which the mark is "presumed" dead. But that presumption can be refuted by the trademark owners showing they were just retooling or had other legitimate reason for not using it in the interim.
A trademark registration, on the other hand, is another matter. A registration may expire. The proprietary rights in the mark can and very well may continue even if the registration expires--provided the mark has not in fact been abandoned, and provided it continues to be used appropriately. But the protections that go with the registration will be lost.
It is in relation to the REGISTRATION where the section 8 issue comes in. Periodically you have to affirmatively show that you haven't abandoned your mark to keep your registration alive.
(You might find this newsletter article on trademark (registration) renewals informative:
http://www.invention-protection.com/ip/publications/docs/Trademark_Renewals.html )
As for your rights as a licensee....
It's been a long time since I dealt with the issue of a licensee acting for the licensor, but I do know that in certain situations this may be done if you are an exclusive licensee. Speak with a trademark attorney about your options -- preferably one who's also familiar with IP issues in bankruptcy as well as licensing.