Tokens on Ethereum have a built in security mechanism called "allowance". Before our smart contracts can interact with your tokens, you must give the smart contracts permission to do so. Enabling an asset is also commonly called "setting allowance".
You have to set allowance exactly once, per asset you would like to deposit. Once the transaction has confirmed, you can freely deposit as many times as you would like.
Pro tip: Take advantage of our gasless deposits! With gasless deposits, dYdX pays the gas fees for your deposit. Now, the only gas you have to pay to use dYdX is when enabling an asset for the first time.