I believe the use of the lock API in DDA is optional.  The engine will internally apply a lock as it writes to a row.  There may be cases when it is helpful to lock a row yourself--to coordinate with checking other rows/tables, perhaps--but it isn't required if you're just making a simple update or delete, in most cases.

However, due to the internal use of locking you might still encounter errors when the engine attempts to lock a row if other connections are also contending to modify the same row.  You may need to catch the error and execute a back-off-and-retry of the operation in some way (automatically, or let the user retry).