Postmodifier of the noun phrase or what?

[stella1977]

e.g.I remembered the room BEING USED only once.
In the above given example, is 'BEING USED' (which is the present participle passive) used as a postmodifier of the noun phrase 'the room' or a complement of whatever?Any suggestions?
Thank you!

[Soup]

Post-modifier,

I remember that the room was used only once.
I remember the room being used only once.

[stella1977]

Soup,THANK YOU!

[Soup]

You're most welcome.