Your staked ANKR will be locked for 90 days initially as you earn rewards. After this time, you are able to claim your accrued ANKR rewards or restake them.

This is stated in our article about ANKR staking: https://medium.com/ankr-network/new-ankr-token-staking-how-to-get-started-ae1e8ef8bcba

For more information, please refer to the article attached above :)