Like anything, we can lose it if we don't use it and practise is important to maintain full range of motion.
When you work on your hands:
1.Work with a hand that is warm. Give the fingers and hand a warming rub before you start. Massage the small muscles between each joint.
2.Work slowly for each joint of every finger to create a gentle stretch and release the muscle tension causing restrictions.
The following are a few videos we have tried and like.