lock sth away
phrasal verb with lock verb uk/lɒk/ us
informal to put money in a place where it is not available to you for a long period:
lock sth away for 5 years/20 years, etc. We asked three financial advisers what they would recommend for someone who is prepared to lock the money away for 10 to 15 years.
Bonds lock money away for between one and five years but tend to pay higher rates of interest than instant-access accounts.