Yoga Sutra 1.11

अनुभूतविषयासंप्रमोषः स्मृतिः ॥११॥

anubhūta-viṣaya-asaṁpramoṣaḥ smṛtiḥ ॥11॥

1. anubhūta: experienced
2. viṣaya: objects of sense perception
3. asaṁpramoṣaḥ: not letting escape or not being lost
4. smṛtiḥ: memory

Memory is when perceived objects are not forgotten, but come back to consciousness through impressions.

OR

Recollection is mental modification caused by reproduction of the previous impression of an object without adding anything from other sources.

Smriti - memory is the fifth vritti of the mind. It is of two kinds; conscious memory and subconscious memory. Conscious memory involves the recollection of things that are already experienced in past. In subconscious memory, one remembers things unconsciously. This is also of two kinds, one is imaginary and another real. When we see a dream, which is not true or real, that is of a accumulation of something imaginary or fancy. But it is based on something we previously watched, seen or imagined, not happened in real. But when we realize or remember something that has happened before and our mind has perceived through a sensory organ, it could be eyes, ears, skin, tounge or nose. In such cases we don´t grasp these things consciously, but unconsciously our sensory organs pick it up and store it in the mind. And when we face a similar contact, memory of the past experience arises if the experience is not allowed to escape from the mind. This is like a dejavu, not sure though if it is exactly the same. It is one of the modifications of consciousness and is therefore classed as a vritti.

References

• Four Chapters on Freedom by Swami Satyananda Saraswati, published in 1976.
• Memory 1.11
• Sutra 1.11 at swamij.com