The current workflow is for an admin to register a student. Teachers give the students an enrolment key to gain access to their courses.
I see 2 problems:
1. Student registration is for the whole site, not for each course. Can we not add students to a course the way we do with teachers?
2. The enrolment key can be open to abuse, especially in paid courses. Can we have a double-bind method -- students registered to a course and accessing it with an enrolment key?
Is this feasible?
What you are talking about here is perfectly feasible and planned for the future. If it isn't already in http://bugs.moodle.com then please log a new feature request there. The future comes even faster if people send me code along with their requests. 
In the meantime, the enrolment key system need not be open to abuse. If you think the key is being abused, just unenrol the offending student and change the key.
(By the way, this is not the best forum for feature requests...)
In the meantime, the enrolment key system need not be open to abuse. If you think the key is being abused, just unenrol the offending student and change the key.
(By the way, this is not the best forum for feature requests...)