Collocations for indispensable - adj.

be, prove
become
make sb/sth
He had soon made himself indispensable.

consider sb/sth

absolutely

for
Written sources are considered absolutely indispensable for today's history teaching.

in
These drugs are almost indispensable in the fight against the disease.

to
skills which turned out to be indispensable to her career

Indispensable is used with these nouns:
prerequisite, tool