Mount gach mounts: How long they last?

I'm interested in some flying mounts. But if the mount gach gives me some 7days or 30days mounts for 4.5k nx, it's a waste. I'll rather buy a 90 day cover from cash shop then(does the soaring work on nx covers???).

Soaring works on the Helicopter and the Teddy Balloon.

Edit: I just saw several NX mounts being available as a coupon in the FreeMarket. Most of them are 90-day.