Hi Guys (& Gals)'
Another great way I've found to keep both film and paper developers fresh for many months is stored in wine casks. That is, the inner plastic lining (usually an aluminised plastic bag) from 'boxed' wine is emptied first (fun!), washed well and replaced with the developer of your choice.
I use both the 4 litre and 2 litre casks depending on volumes needed - if you only have 1 litre made up, this can go into the 2 litre cask. Simply lay the bag down and carefully release the tap while compressing the bag to release the last of the air.
I have some Ilford MG paper developer in a cask and still using it after 12 months - it still looks the same colour as fresh stuff and still works like fresh.
Home mixed Beutler film dev is made up as part A & B in separate 2 litre casks - they easily last 6 months or more.
After you've filled the wine bag you can replace it in its original box, suitably labelled. Be very careful that you keep them away from food prep areas for obvious reasons - label them very obviously and mask out the original labelling.