Help on a licensing management service

I'm thinking whether to develop a licensing key management service in-house or use a commercial product. The in-house solution would require the user to run on his pc a script we provide and send us an email with the generated file. It'd be a bit more amateurish than a commercial solution, that would make a license check on a server at installation.

I'm not really sure what's the best/cost effective solution for a small company, that has to handle less than 100 licenses. Also I'm not familiar with the most famous commercial services, any pointer would be really appreciated. Googling I found QLM, Reprise and a few others, not really sure what to do. Any of you guys has some experience with this?