I have a Windows 7 ultimate laptop computer, recently I intend to use BitLocker to encrypt the Windows 7 partition. The depressing part is that I can't encrypt this partition directly with a password, Windows requires me to use a USB drive as the startup key, and this situation does not exist when encrypting a data partition. I hate having to carry a USB drive with me and I want to be able to start BitLocker encrypted Windows 7 directly with a password. Can someone tell me if this is possible?
By default, Windows 7 can only be started with the BitLocker recovery key or a BEK file. A BEK file is a key saved on a USB drive that allows you to start a Windows 7 computer without entering the BitLocker recovery key. Only Windows 11/10/8 can be started by entering a password, because the password-based startup feature is not implemented in Windows 7. Is there any way to boot a BitLocker-encrypted Windows 7 with a password instead of using a startup key USB drive or the BitLocker recovery key? The answer is to use Hasleo BitLocker Anywhere. You can find the complete steps below.
Step 1. Download and install Hasleo BitLocker Anywhere.
Step 2. Launch Hasleo BitLocker Anywhere, right-click the Windows drive letter (usually C:), then click "Turn On BitLocker".

Step 3. In this step, you are asked to choose how to unlock the Windows drive at startup. Please select "Enter a password" to start the computer.

Step 4. Now you are required to specify a password for encrypting the drive. Enter the password and click "Next". You should choose a password that combines uppercase and lowercase letters, numbers, spaces, and special symbols.

Step 5. you will be asked how you want to back up the BitLocker recovery key. You can save the recovery key to a file or print a copy of it, then click "Next" to continue. Please note that anyone can use the recovery key to gain access to the drive, even if they do not have the password you created in the previous step. Therefore, please do not disclose it to others.

Step 6. Now a pop-up will appear asking you if you want to reboot into pre-OS to encrypt the Windows partition. Click "Yes" to continue.

Step 7. Another pop-up will appear asking you if you want to create a WinPE image to continue. Click "Yes".

Step 8. Hasleo BitLocker Anywhere is starting to build WinPE. This may take several minutes. Please be patient.

Step 9. After successfully building the WinPE image, Hasleo BitLocker Anywhere will prompt you to reboot your computer. Click the "Yes" button to allow it to restart your computer.

Step 10. Hasleo BitLocker Anywhere will now reboot and enter pre-OS to encrypt the contents of the selected drive using BitLocker Drive Encryption. The encryption process could take a long time to finish depending on the drive size, so please be patient. If you do not want to wait until encryption is complete, the "Shut down the computer when the operation is completed" option is a good choice. Just check it.

Step 11. After encryption is complete, click the "Finish" button to close the window.

Step 12. Now you must enter the BitLocker password before you can start Windows 7.

To sum it up, by default, Windows 7 does not allow you to enter a BitLocker password before reaching the login screen, even if you are using Windows 7 Ultimate or Enterprise Edition. Fortunately, with Hasleo BitLocker Anywhere, you can boot a BitLocker-encrypted Windows 7 using a password, instead of a startup key USB drive or BitLocker recovery key. If you prefer to use a startup key USB drive to encrypt and boot Windows 7, please refer to the user guide: How to Encrypt Windows 7 Partition and Start the BitLocker Encrypted Windows 7 with a BitLocker Startup Key USB Drive?