Hi.
You say "key"... do you mean the 48-digit recovery password?
If you mean that, yes, it is possible that a machine demands the recovery password on each boot in case the TPM is unable to release the key.
The TP might decide that you bios settings have changed and thus, won't release the key. or, you have erased the TPM or, you have changed its operation mode to 1.2 or such things.
So 1st, explain what you enter and if it's possible that some bios settings have been changed (or the bios has been updated)