The deadline
Will my Memories be deleted?
Only if you have more than 5 GB of Memories AND you are not paying for extra storage. Below 5 GB nothing happens at all. Above it, whatever sits over the limit is deleted when the 12 month grace period runs out. The oldest photos are kept, so the newer ones go first.
Short answer: only if two things are true at the same time. You have more than 5 GB of Memories, and you are not paying for extra storage. If both are not true, nothing happens.
If you are under 5 GB you are not affected at all, no matter how many years you have used the app. Swedish broadcaster TV4 estimated the limit at roughly a thousand photos. But video is heavy, so a couple of hundred clips can fill the same space on their own.
So you do not have to guess. You can check. Open your profile, tap the gold box for Snapchat+ and scroll to the row with the cloud icon. It shows how much of your storage you are using, and if the number is red you are over the limit. If you are over, Snapchat also shows a box at the bottom of Memories with your own numbers. We have made a guide with screenshots, and although the page is in Swedish the pictures show it tap by tap: sparaminamemories.se/kolla-snapchat-lagring
If you are over the limit you get 12 months of temporary storage. Snap has not said when those 12 months start counting, so nobody can give you an exact date. After that, whatever exceeds the limit is deleted. The oldest photos are kept and the newer ones go first, which is the opposite of what most people assume. It is not your childhood that is most at risk, it could just as easily be last summer.
One detail that applies even if you pay: the moment you stop paying, a clock starts. Snapchat says you then have 48 hours to subscribe again before the Memories above the limit are deleted. An expired card or a forgotten renewal is enough.
And here is what makes the question worth taking seriously: deleted Memories cannot be brought back. There is no bin with a grace period. Snapchat has said so themselves.
If you would rather not depend on remembering to pay every month, the alternative is to get your export out and keep the memories yourself. Asking for it costs nothing, and you can decide later what to do with it.