How can I make bpr to surpport "Time Travelling"

[jackyhawk]

As the user behavior time window is sliding, and at different time,the user bahavior should have different effect (such as one click happened yesterday and another click happened 30 days before ,should affect the user factor quite differently).

And my question is how can I make it in BPR?

Can I just update the factor (old) with a decay rate?
such as
new_factor = old_factor * 0.99999999 + some_loss_error

thanks very much