Ok, I figured out where to check. In the Purchases tab there is a Gifting History button.
For some reason it wasn't showing up earlier today, there were some store issues going on when I looked for it earlier:
There still seems to be some issues with the button, because when I visited my purchases tab later it was missing:
But once you click the button you get the following information:
If you are a non support you have 2 options:
First option
Sweeping lens (most commonly used in higher elos)
You can switch your trinket for a sweeping lens to clear wards. This allows more baron control or you can clear wards to force a enemy to come near a bush so you can kill them. Of course you don't want to use it versus a team comp that has champions who can easily check a bush on high range (Lux/Lucian for example)
Second option
Vision ward
If you need permanent map control and/or the cleanse of a normal ward you can use a sight ward. If positioned right a sight ward can grant you vision for a really long time (deathbush for example). I usually take this option on most non supports, since you got a permanent ward on comparatively low cooldown and you can also clear a dragon/baron area. It just allows more utility.
Of course you can also upgrade it to a normal sightward but that isn't that benefitial. Of course it's a good thing if you are still in the laning phase after 30 minutes but generally the rule boot upgrades > trinket upgrade counts. And if you could afford both you can easily buy a chain west/pickaxe/blasting wand situational to the champ you are playing.
You usually want to upgrade your trinket last or if you got 475 gold to spend and you have no problem of farming that gold up again after you leave the base.
As a support both rules count but there are some exeptions
First option
Buy it if you are a support that relies on bush stealth (Blitz/Thresh/Leona) and you can instantly charge/grab an opponent that comes to close.
Second option
Buy it after you finish your sightstone so you have 3 normal wards and 1 pink ward almost all the time.
Best Answer
The Loot tab will only show you your ward skin shards, which you need to upgrade with orange essence to activate (click to enlarge):
There's currently no place to see all your ward skins besides the lock in screen. The easiest way to look at them is to create a custom All Random game. This will give you one full minute to look at your ward skins; then you can simply quit: