Are you talking yeast starters with just unfermented wort? If so, can them and they will last a long time in the fridge. With the "canning method" I have kept starters for 6 months or longer before use.
Brewing since 1989 - BJCP National Rank
Fermenting: Saison Autome, Cherry Mead
Conditioning: Dortmunder Export, Belgian Dubbel, O-fest, Vienna Lager
On tap: CAP, Cider, Impy Cherry Stout, Rye Dunkel Bock, Belgian Chocolate Stout, Hopslam! Clone
Newly Bottled: Belgian Blonde, Belgian Quad