The correct term is not "lifetime"...it's "permament" and even that only means until death of the payor, cohabitation of the payee, or remarriage of the payee, or a substantially changed circumstance like retiring at a reasonable age (65 not 55) and your income goes down etc.
The law is quite varied and complex and judges opinions vary greatly but the two important factors in my opinion are ages of the parties and length of marriage. I advise clients generally you have to go 15 years to be reasonably assured of success. There are lawyers who will seek it for less time married and base it on a specific case that has no bearing to their case at hand but if contested experience has taught me that judges want to see a longer term of marriage.
Then there is age. What if you are married 15 years and your only age 40? Its not fair to make a person pay 25 years to retirement when they were only married 15. Judges in that situation will often make a long term ruling on alimony (8 - 15 years). In short, there are no free rides or total guarantees in life.
Lastly, Income is very important. One party has to be able to earn considerably more then the other in order to support the idea of alimony.