Signing an NLI with a school does not guarantee you playing time on their team. While earning a scholarship with a college program is a good sign that you are good enough to play for that team, the only thing that the NLI can guarantee is the scholarship money you will earn that year.
By signing an NLI, a high school athlete is committing themselves to that program for at least one year.
The recruiting process usually ends when an athlete signs an NLI because other colleges are not allowed to recruit athletes who have signed with another school.
Since the NLI will not guarantee you playing time at the school, it is important that you continue to work hard to earn your time on the field.
High school athletes who have signed the NLI have no doubt formed relationships with the coaches at the school, and should know what is expected of them as a member of their team. Just like the other recruits and veterans on the team, you will need to work hard and demonstrate to the coach why he should give you playing time. You have to earn it.