In the context of our key-value store, let's add an LRU cache to handle scenarios where memory capacity may not be sufficient to hold all keys. Check out the following Python code block which defines a basic implementation of an LRU cache. The cache is created using Python's OrderedDict which maintains order of insertion. This will allow us to remove the least recently used item when the cache reaches its capacity.

Two main methods are defined in our implementation:

1. get(key: int): This method returns the value of the key if it exists in the cache and moves the key to the end to mark it as recently used. If the key doesn't exist in the cache, it returns -1.

2. put(key: int, value: int): This method adds a particular key-value pair to the cache. If the key already exists, it updates the value and moves the key to the end to denote recent usage. If the cache is full, it removes the least recently used item before adding the new key-value pair.

Think of a practical use for this algorithm - it's similar to how memory is managed in cloud-based AI applications that require huge data processing. Data that is accessed often (hot data) stays in the cache and data that is rarely accessed (cold data) is kicked out as the cache fills up. This optimizes memory usage, providing quick access to frequently used data.

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    print(cache.get(4))        # returns 4

from collections import OrderedDict

​

class LRUCache:

    def __init__(self, capacity: int):

        self.cache = OrderedDict()

        self.capacity = capacity

​

    def get(self, key: int) -> int:

        if key not in self.cache:

            return -1

        else:

            self.cache.move_to_end(key)

            return self.cache[key]

​

    def put(self, key: int, value: int) -> None:

        self.cache[key] = value

        self.cache.move_to_end(key)

        if len(self.cache) > self.capacity:

            self.cache.popitem(last=False)

​

if __name__ == '__main__':

    cache = LRUCache(2)

​

    cache.put(1, 1)

    print(cache.get(1))        # returns 1

    cache.put(3, 3)            # evicts key 2

    print(cache.get(2))        # returns -1 (not found)

    cache.put(4, 4)            # evicts key 1

    print(cache.get(1))        # returns -1 (not found)