Filament long term storage
In theory, most filaments don't go bad.

It is however always a good idea to store filament dry. To enforce this, some use racks in a well-heated room, others are blessed with very dry weather overall. And others are forced to use dryboxes. Dryboxes can keep the filament reasonably isolated from the surrounding air and so prevent moisture interacting with them. It is also a good idea to store them out of direct sunlight, as UV light might destroy color and/or the plastic.

More information on why to use them is for example at the question Which filaments actually do need to be stored in a drybox?

A couple construction videos using an IKEA box and a bit of foam were offered by Tom (Thomas Sanladerer) and CNC Kitchen (Stefan Hermann) in the last year.

But fear not: most filaments - PLA included - can be freshened up again! Just bake them at a low temperature or store them in a dehumidifier. For PLA, keep the temperature at below 80°C. A couple hours should get all the moisture that has seeped in out again. The Quality might not get back to that of fresh filament in all cases, but you might at least regain reasonable to good printability.