You need to earn about 40 “credits” or “quarters” by paying Social Security and Medicare payroll taxes while working — equal to about ten years of work — to get Part A services without paying premiums. Your payroll taxes have already covered the premiums.
Not having worked long enough to “qualify” means that you can’t receive benefits for Medicare Part A (hospital insurance) without paying premiums for them.
It’s possible to qualify for premium-free Part A services if you don’t have enough credits based on your spouse’s work record. That is if you’re 65 or older and your spouse is at least 62. In some instances, you may qualify on the work record of a spouse who is dead or divorced.