Can i copy any lesson from one course to another?

Both.  I think the security protection at the lesson level needs to be similar to the protection of the course - or else the owner protection is easily circumvented.

By having security that stops a collaborator from copying a course (currently provided) as well as not allowing copy of a lesson (not provided), the combination of Rise and SL is extremely valuable.

Without the lesson protection, the client can transfer lessons from my Rise account to their own course and then export it freely.