Into the Weeds: Potion Storing and Ergonomics

Reagents and potions are a cornerstone of the Scarterran economy.
Adventurers and militaries that can afford them use potions routinely.
When it comes to divine potions, Healing ●●● potions are in high demand and most temples that can afford to do so make it a point to stock up on them.
Augmentation ● are nearly as popular because they are useful to every adventurer and warrior and fairly cheap. These potions are commonplace enough that many athletics contests and tournament fights will have magical diviners checking to make sure no one is sneaking a "performance enhancing potion" into a competition, at least if there is prize money involved.
Purification ●●● potions are fairly popular with adventurers but less so with militaries. Divination ● potions are popular with adventurers and guards of VIP targets that regularly have to content with magical intruders.
In the world of arcane potions, mobility enhancing potions such as Expeditious Movement, Spider Climb, and especially Fly are popular among elite soldiers and adventurers. A lot of gnome adventurers and other adventurers with short legs keep several potions of Fast on hand just so they can keep up with their taller companions.
Potions of Protection, Shield, and Heroism are popular with warriors of all stripes. Heroism can augment social actions and can even be used by high end diplomats though this is rare because 1) it's expensive, and 2) high level diplomatic meetings often screen for magical spells and effects.
Potions of Disguise Self and Invisibility are popular among spies and criminals and among those who hunt spies and criminals.
Other potions are situationally useful and can be made fairly easily but it is unlikely that any one stocks up on them on the off chance a customer wants to buy them, these potions usually have to be commissioned. It is rare and prohibitively expensive to make potions with ●●●● and ●●●●●. A person to lucky to own one or two such potions. You are almost never going to find anyone hoarding these things.

Proper Potioneering 101

Long-term, potions are generally stored best in glass containers. A potion in a glass bottle with a wax sealed stopper will last about two years before the potion loses any potency. Then it will be at about 2/3 strength. After two more years, a potion will be at 1/3 strength and then it will become a foul tasting tasting muck with no magical properties after another two years.
A wax sealed stopper is a pain to open during a melee and glass can easily break accidentally (or purposely if the enemy is trying to strike at the potion bottle). A lot of adventurers and elite soldiers keep their potions in a metal container with a flip top lid. This is more durable and generally convenient to open in a high stress situation such as a melee.
A potion in such a metal container like this will degrade about three times faster than a potion in the aforementioned glass container, but going into battle, a character can be almost certain to want to drink it quickly anyway. Most adventurers and soldiers who can afford to keep a stock of potions keep some potions in glass bottles deep in their packs (insulated with cloth). If going into battle, and near certain to need to use some of their favorite potions, they will transfer some potions to metal containers clipped to their armor beforehand.
If it turns out, they didn't need the potions, they can always move the potions back into glass containers, or not. All that said, most adventurers are guaranteed to want ready access to a healing potion within the following year, so the shelf life is rarely an issue.

Potion Equivalents

Potions can come in the form of a powder instead of a liquid. This is moderately more expensive than a conventional potion Powders last about half again as long before degrading compared to liquid potions but the main reason people use them is for situational convenience.
Powders are activated when applied to an area by sprinkling it over something. A potion that is dumped out and not drank is wasted. Sprinkling a healing powder on a wound is both simpler and less invasive than force feeding an unconscious person a healing potion.
Scrolls hold stored spells. Normally, only divine spell casters can activate scrolls and only mages can activate arcane scrolls. Scrolls will normally handle the test of time much longer than potions, but they can easily catch fire or be ruined by moisture or be accidentally torn.
A wand or wand-like stores many spells in a single item. Divine wands can normally only be activated by divine spell casters and arcane wands can normally only be activated by mages.

Do players really have to keep track of this?

Not if they don't want to.
It is assumed that in down time, player characters will make intelligent decisions with their potions much how it's assumed an adventurer will pack his backpacks and other containers are packed so items an adventurer will need quickly are easily accessible while down time items are packed deeper.

What about "potions"s that are not actually potions

Magical oils and powders last about three times as long as potions, but they still last longest in sealed glass containers.
Magical candles last about ten times as long in storage as potions, but they still last longest in sealed glass containers.
Most scrolls are made on top quality paper or vellum. They will typically last ten times as long a potion in long term storage, but only five times as long if they are stored in a high humidity environment, and up to a hundred times longer if they are kept somewhere dry and secure like a tomb vault.
A lot of larger temples or fincially well off feudal covens have a special chamber built specifically for the long term storage of scrolls and these groups will quietly horde magical scrolls.