An Account Bound item belongs to your account for good. You can wear or use it, but you can't trade it, list it on the Marketplace, or gift it to anyone. Account Bound is permanent for that copy and never counts down.
Which items are Account Bound?
It depends on how you got that copy. Common sources:
Pulls paid with Promo Grab Tokens.
Blind Boxes you receive as items, for example from events, Crew tracks, offers, or the former Season Pass, and any free daily Blind Box pull.
Most items from the Threads Exchange.
Signature Items, which can't be traded.
Some event rewards, gifts from Highrise, and Pals such as Boo Buds.
The item's info card shows the Account Bound label.
Why can I trade an item someone else has, but not mine?
Because copies differ. If they paid Gold for their pull and you used a free Blind Box, their copy can be tradable while yours is Account Bound. If you own both kinds, the trade window only counts your tradable copies, so it can show "0 Owned" for something you're wearing.
What can I still do with Account Bound items?
Wear or use them.
Recycle them, if they have a recycle value.
Count them toward Blind Box collection progress when you get them from that Blind Box.
What about Creature Club items?
Items that come with a Creature Club NFT are marked NFT Account Bound. You can wear them in Highrise, but they can't be traded, listed, or recycled in the game. See What is Highrise Creature Club?
Can Support make an item tradable?
No. Account Bound status can't be removed from an item. If you think a copy you paid Gold for was marked Account Bound by mistake, contact Support with your username, the item name, and roughly when and how you got it.