When you first create a free-to-play OSRS account you will be greeted with the message “you cannot sell that item until your account is older”. This restriction only shows up when you try to buy and sell certain items that are frequently abused by botters. This restriction was added to the game to prevent bots from creating mass accounts and abusing low-level money-making methods to make quick gold before their accounts are banned. There are a few ways to circumvent these restrictions for free and a few ways to circumvent these restrictions by paying money. Overall - these restrictions make the game a better place and have a net positive effect on the game!
To remove this restriction without paying money you need to either complete enough quests to get 7 quest points or play F2P OSRS for 24 hours. Getting 7 quest points on a free-to-play account only takes around 20 minutes if you are skilled so that is the optimal way to do it. To get 7 quest points we suggest completing the following quests:
Another method of removing this restriction is by simply paying $10.99 USD for a month of membership to instantly remove this restriction. You can also purchase a bond and redeem it for 14 days of membership to remove the restriction.
Overall - “you cannot sell that item until your account is older” is an error you get when your OSRS F2P account is too new to use the Grand Exchange. To solve this you can either get 7 quest points by completing Cook's Assistant, Sheep Sheerer, and Romeo and Juliet; you can play the game for 24 hours of in-game time, or you can purchase a membership through either a 1-month code or a 14-day bond membership!