1)
When was our lowliness?
1.
Rashi: In Egypt.
2.
Radak: When we were exiled from the land due to our sins. This can refer to Galus Bavel, or our current Galus.
2)
What did Hashem remember for us?
1.
Radak: The Bris with the Avos - "v'Af Gam Zos bi'Hyosam [b'Eretz Oyveihem]" (Vayikra 26:44).
2.
Malbim: All the many miracles that Hashem did for us in the past to remove us from our afflictions, they are guarded for us [to do again] in the future.