Question about Impulse

I haven't had Sins on my computer for about a year or two at this point and just recently decided to put it back on my computer. I bought a hard copy of it but don't have the discs with me at my new house. I was in the same situation a while back and since I had registered just used Impulse to download a copy of it. However, now that impulse seems to be gone (unless I'm mistaken), how would I go about doing this again?