If you need a specific older version like 20.8.4 , you can find it in the official Image-Line forum archive . Note that you still need a valid license to unlock it.
One of FL Studio's best features is that once you buy any version, you get free updates for life . If you need a specific older version like 20
If you have purchased a license, you can unlock the full version by simply logging into your account within the software or by using a registration key (RegKey) file from your user profile. FL Studio 20: Unlocking full version with regkey If you need a specific older version like 20