Display something in postbit if subscription purchased?

[007]

I know somehow vBulletin knows when someone subscribes, but what is the conditional I could put in postbit to display something based on whether or not somebody is a subscriber to X subsctiption ID??

Is this possible in a template mod or do I have to hack for it?

Thanks.

~007

P.S. I should mention that I am talking about a subscription that doesn't change the usergroup, so conditionals based on usergroup won't help.