In NBA 2K21 MyTeam, cards can only be used for a specific period of time. The reason is that each card has a contract duration. After a player's contract expires, the only way this card can be used again is to renew the contract. So how do you renew a player's contract in MyTeam? Let's see what you need to do.
First, go to the MyTeam home screen and navigate to your active lineup. After that select a card by pressing A/X. Here you will see a list of options to choose from. Select Apply contract and you will be able to add all available contracts that are in your MyTeam collection.
If you don't have any contracts in your collection, you can purchase new ones by selecting the Apply Contract tab when selecting a player on the MyTeam lineup screen. You can also receive contract cards in MyTeam packs. Contract cards can be either bronze (three parts), silver (four parts), or gold (five parts).