What happens to tokens after they are unlocked?

They will continue to be staked and count towards your receipt of tokens. Their token weight will continue to be the same as they were when locked. For example, if you lock tokens for 3 months they will have a token weight of 1.25. After they unlock you can withdraw them, but if you choose not to, then they will still count towards liquidity mining. You would only choose to lock them again if you wish to increase their weight to something higher than their previous token weight.