I've had several items stay far, far, longer than a day in a vender's shop before. I am not sure if they stay indefinitely, though they seem to take a lot of time to go away.

There is a list of items that are either permanent, as in they will never go away ever, or persistant, if they fall on that side of things they too will not go away ever, if they don't they will.

http://www.uesp.net/wiki/Skyrim:Permanent_and_persistent_items

I've had several items stay far, far, longer than a day in a vendor's shop before. I am not sure if they stay indefinitely, though they seem to take a lot of time to go away.

The UESP wiki lists two distinct types of permanent items:

Type 1 - Permanent (fully)

• Keep their RefID number, when dropped into the world
• Do not lose any of their persistent traits when dropped into the world

Type 2 - Permanent (until dropped)

• May keep or lose their RefID number, when dropped into the world
• Lose any or all of their persistent traits when first dropped into the world.

List of permanent items

The following items were found to be fully permanent:

1. Aetherial Crown [DG]
2. Ebony Blade
3. The Gauldur Amulet
4. Zephyr [DG]

The following items were found to be permanent until dropped (or placed on a weapon plaque):

1. Calcelmo's Ring
2. Declaration of War [DB]
3. Eduj
4. Emerald Dragon Claw
5. Halldir's Staff - the one you get from Halldir's ash pile, not the one which drops near it
6. Ironhand Gauntlets - looted from Hajvarr Iron-Hand
7. Iron Dragon Claw
8. Journals of Ralys Sedaris [DB] - all volumes
9. Klimmek's Supplies
10. Letter from a Friend - all instances
11. Okin
12. Ruby Dragon Claw
13. Saerek's Skull Key - only if you do not use it to awaken Otar the Mad (awaken him with shout or rune spell instead)
14. Staff of Hag's Wrath
15. The Aetherium Wars [DG] - only the first copy, obtained before or during associated quest
16. Torsten's Skull Key - only if you do not use it to awaken Otar the Mad (awaken him with shout or rune spell instead)
17. Whiterun guard's armor, shield, helmet, gloves and boots - looted from Mirmulnir

Note: Permanent weapons may fail to prevent corpses from disappearing, although they will remain in respawning containers.

I've had several items stay far, far, longer than a day in a vender's shop before. I am not sure if they stay indefinitely, though they seem to take a lot of time to go away.

I've had several items stay far, far, longer than a day in a vender's shop before. I am not sure if they stay indefinitely, though they seem to take a lot of time to go away.

There is a list of items that are either permanent, as in they will never go away ever, or persistant, if they fall on that side of things they too will not go away ever, if they don't they will.

http://www.uesp.net/wiki/Skyrim:Permanent_and_persistent_items