The expiration date in a novel could potentially refer to a deadline for something within the story, like a character's mission or a prophecy to be fulfilled. For example, in a mystery novel, it might be the time by which the detective must solve the case before more harm occurs.
In most manga, the idea of women having an expiration date doesn't exist. Manga creators focus on diverse traits and experiences of female characters, not on setting a time limit for them.
In a thriller novel, the expiration date could be related to a dangerous device or a threat. The protagonist has to stop the bad guys before the expiration date when the device will cause mass destruction. This keeps the readers on the edge of their seats as the time ticks down, adding a lot of suspense to the story.
No, the idea of women having an expiration date in manga is quite absurd. Women are represented in various ways and at different stages of life without such a limiting concept.
I don't think women have an expiration date in manga. As for reading it for free online, that might not be legal or ethical. You could try looking at some legal manga platforms that offer free trials or limited free content.
The expiration dates in novels might refer to things like the relevance of the themes over time. For example, a novel set in a very specific time period with dated social norms may seem less relevant as time passes. If it's about a particular trend that has expired, readers might not connect as well.