I still have the tin I got about 7 or 8 years ago, use so little of it that I aint gettin my undies in a kink about the cost.

and yes, those fitted rain covers with the velcro on them are handy, I finally got one after using plastic bags for a while and it just fits on better and I keep it with my stuff now as a habit. Just one of the foibles of a leather seat, if taking care of it in this manner and reducing the sagging over time is important to you.