I need to lock in for this exam I'm taking tomorrow.
The missile's path is now locked in.
1 more example
The best ride of the day was one that Robert got - really locked in, screaming at the top of his lungs.1966, Bruce Brown, director, The Endless Summer:
US A sleepover party, usually held in a public place such as a church or school, in which the participants are not allowed to leave until the next morning.
The youth group will have their annual lock-in this weekend.
2
Ireland, UK An illegal but widely-tolerated invitation-only gathering in a pub, after the end of licensing hours, to allow regular customers the opportunity to enjoy further drinking time.
He was a lunatic drunk and started sing songs that lasted into the early hours of the morning and resulted in many weekend lock-ins in the village pub.2009, Annette J. Dunlea, Always and Forever, page 53:
3
Business A situation in which a business has adopted a certain standard or product from a specific manufacturer and integrated it into their process, thus making it very costly to change to a different standard or supplier.
vendor lock-in
4
Business, Finance The situation where an investor cannot trade without incurring an undesirable penalty such as taxation.