The most used token standard on the Ethereum blockchain is the ERC-20 standard. This standard has been widely adopted and is currently the leading industry standard. The standard has certain rules that any token must incorporate and comply with to be compatible with other ERC-20 tokens.
The Token Allowance Permission found in the ERC-20 standard grants permission for a third party to use smart contracts on behalf of the user, once it has been allowed. Once the token has been allowed to be used by the third party like MetaMorph.Pro, it is then tradable on the platform and the user can place buy and sell orders. Allowing a token does not mean giving up control of the tokens. It only means that you allow the third party to transfer tokens on your behalf – transactions will always need to be approved by the user before they are performed.