Originally Posted by NoSidNoStar

Your Hilton points did not expire because you kept renewing them with a stay. If you would not stay for a year, the point will expire.
As a matter of fact, Hilton has even a policy to just let you buy points, I think by spending $50, to keep them renew, when you are did not stay during the last year.
Marriott points, so far, never expire, even if you don't stay for over a year.