As a manager, what do you do if you have an enthusiastic employee who is capable to learn new things and implement them well? Will you help him/her to get promoted or just use him for only finishing his/her limited tasks?

give him or her achance to practice his by trainning him let him to show his ability dont leave him alone just observe and then yuo can assese how do you take abenifet

I will give him more and more tasks to know about his ability and try to make more outcome

it depends on mutual benefits , organization and employee

I will help him to promote.

I will surely provide him or her with the right opportunities, based on their skills.  

i will surely help him/her if it really benefits our company

It is a very integral part of a manager's profile to motivate and nurture talent in his subordinates, helping them grow and move up the corporate ladder. I would definitely motivate the subordinate and provide him or her with the right opportunities, based on the skills for him/her to excel and grow as an individual as well as a professional.

will help him/her to get promoted

A solid high pyramid starts from the base. Unless you take care of the employees under your supervision you will never be promoted and doing this can be by the following steps :

1. Setting a clear guide lines to the nature of work and never confuse them by undesirable tasks.
2. Always make a void for a self challenge for the employee in order to kill the routine of the everyday tasks.
3. Leading by example is the best way to get his best and maintain your level of achievment stipulating that you also develop yourself.
4. Always be share the credits of the good job with the exquisite achievers.
5. Always give your frank feed back in order to rectify any of their misguidances and misbehaviours.
6. Respect the code of condut between you.

Regards

• Encourage him
• Motivate him 
• Follow closely its activity
• Give him means to developp its skills and abilities
• Train him
• Promote him
• Urge him to take responsibility

On my point of view, promote him/her to become a Trainer. He/She could impart his/her knowledge,skills, and positive outlook to the other employees in the department.