In the Hilton Honors program, If you do not have eligible activity in any 24 consecutive month period, you may be removed from the Program and are subject to forfeiture of all accumulated points. But, at the discretion of the program, you may be permitted to remain in the program and be removed after five years of inactivity.
But, to be on the safe side and keep your accumulated Honors Points, you must take one of the following actions within a 12 consecutive month period:
a. stay at a hotel within the Hilton Worldwide portfolio
b. earn Honors Points through any third party source of Honors Point accumulation, including a Hilton co-branded credit card
c. purchase Honors Points,
d. donate points