Although there exists different studies that relate an advanced age with fertility problems, actually it is still unclear.
In the testicle, sperm production is a permanent process, contrary to what happens in with egg production in females. This is the reason why, freezing sperm as a preventive measure is not so useful as in the case of egg freezing, since egg quality and quantity decreases from age 35 onwards.
Unless there exists a disorder that affects sperm production, in the case of cancer patients who are going to undergo chemotherapy or radiotherapy, or if the man undergoes some kind of surgery (such as in the case of vasectomy), freezing sperm for the future is not required.
Suggested for you: What Is the Process of Freezing Sperm?.