You'd be better off to use new yeast. There is a lot of selective pressure on the yeast in big beers (high ABV, lots of byproducts, etc), so the yeast left over at the end can be very different than the yeast you started with. Reusing it will ferment beer, but you're not likely to get similar results to the last time you used it.
If you want to be able to buy one vial of yeast and use it a bunch of times, then culture up a 2L starter and harvest that into small jars or tubes and use those to start off new starters for brewing with. You can easily get 5 small jars from a single culture (depending on the starter used). I used test tubes for this (testtubesonline.com) and keep them in a rack in my keezer