Well the plum mead could in theory last years. But I don't have enough bottles to rotate through for that.
Did recently order some more swing top bottles though, so I can store a bit more. So I can either let it age for longer or make less frequently in larger batches. I think it will bring my total bottled storage to 18L across several different sizes of bottle and I use 5L demijohns.
The new bottles are the smallest too at just 500ml each, might be better for experimenting with adding sugar at the end though. My partner only really likes sweet drinks and it would be nice to have something she can enjoy too.