Yes
> what?
They can decide you can't use it anymore
They can decide to charge more for it
They can arbitrarily take features out from under you or change how it works
They can read and/or sell/give away/accidentally get exploited and lose your data
They can prevent your extracting your data to move away from them
They can prevent you building or integrating other tools
They control how you can modify or configure the software
...