Use license on Windows and Mac OS X?

Hello there,

I have a quick Q: I purchased a license for Balsamiq Mockup (Desktop) 2-3 Weeks ago but basically I am dual-booting on my macPro.. sometimes I am under Leopard, sometimes I am under Vista (*yuck*). Am I allowed to use my license in both OS'es (not at the same time obviously)?

Cheers and thanks,
-J