How long do lentils last?
Unopened, they keep in the cupboard for about 1 year.
This refers to: Dried lentils.

Shelf life of lentils at a glance
| Storage | Unopened | Opened |
|---|---|---|
| Cupboard | 1 year | – |
Dried lentils are usually fine well past their best-before date but take longer to cook. Store dry and airtight; opened canned lentils keep 1 to 2 days in the fridge.
Past its date does not mean spoiled
These are guide values for food stored correctly. A best-before date is not a throw-away date: many products are still fine after it. Check how it looks, smells and tastes. Mould, an unusual smell or a bulging can are reasons to throw it away. A use-by date is different: do not eat the food after it.