In our Haggadah, in the section of Maggid, the Baal Haggadah includes a passage from the Gemara in Berachos (דף י"ב:) which quotes Rabbi Elazar ben Azaryah interpreting a dispute between Ben Zoma and the Chachomim concerning the Posuk which says "למען תזכר את יום צאתך מארץ מצרים כל ימי חייך," "so that you shall remember the day on which you left Egypt all the days of your life" (דברים ט"ז:ג'). Ben Zoma holds that the words "ימי חייך," "the days of your life" refer to the daytime (when one is obligated to remember Yetzias Mitzrayim), and the word כל"," "all" comes to include the required remembrance at night. The Chachomim, however, claim that "ימי חייך" refers to the obligation to remember Yetzias Mitzrayim in this world (הזה עולם), while the word "כל" refers to the obligation in the world to come (עולם הבא).
With this in mind, it is very strange to note that both the Sefer HaChinuch (מצוה כ"א) and the Rambam, in his Sefer HaMitzvos (מצות עשה קנ"ז), state that there is a Mitzvah MideOraisa to remember and discuss in detail the story of Yetzias Mitzrayim on the night of Pesach (the fifteenth of Nissan), yet neither of them mention anything whatsoever about a Mitzvah to remember Yetzias Mitzrayim on a daily basis during the rest of the year. How can that be? It seems to be entirely against the Gemara (שם). This question becomes even more puzzling if we consider that the Rambam elsewhere (פרק א' מהל' קריאת שמע הלכה ג') seems to follow the view of Ben Zoma, holding that there is a Mitzvah to remember Yetzias Mitzrayim both at night and during the day all year long, while in the Sefer HaMitzvos (שם) he omits any reference to this. There thus seems to be a contradiction in the Rambam as well as a difficulty with the Gemara.
Rabbi Yechezkel Landau, the author of the Tzelach, and the Minchas Chinuch, both resolve the above question in the following manner. They claim that the Rambam held that there indeed is no obligation to remember Yetzias Mitzrayim on a daily basis. After all, the Posuk did not use the word "זכור," "remember," implying a positive commandment to remember; rather, it says "למען תזכור," "in order that you should remember" (דברים ז':י"ח, ט"ז:ג'). They explain that because the Torah did not state the commandment to mention Yetzias Mitzrayim every day בלשון צווי, as a direct commandment, it is not that kind of commandment; rather, remembering Yetzias Mitzrayim should be the result of other actions, such as the many Mitzvos the Torah describes as reminding us about Yetzias Mitzrayim, which will thereby enable us to remember Yetzias Mitzrayim and fulfill this Mitzvah as well.
A different approach is quoted in the name of Rav Chaim Soloveitchik, who held that the Rambam did indeed consider this to be a daily Mitzvah. The reason that he excluded it from his Sefer HaMitzvos, though, is that as he states in his introduction to the Sefer HaMitzvos (שורש ג'), he included on his list only those Mitzvos which will apply at all times, even once Moshiach comes. According to the Gemara in Berachos mentioned above (שם), this particular Mitzvah will not be practiced in the same fashion as it is currently once Moshiach comes, because we will then have to focus more on the final redemption, and the Rambam therefore excluded this Mitzvah from his list.
Some authorities suggests that although there is indeed a Mitzvah to remember Yetzias Mitzrayim daily, this Mitzvah need not be articulated verbally; rather, it may be done in one's mind. The Rambam, however, documents only those Mitzvos which must be verbally or physically done. One such Mitzvah relates to the night of Pesach, as the Posuk writes, "והגדת לבנך," "and you should tell your son" (שמות י"ג:ח'), which involves an action. The Mitzvah which relates to remembering Yetzias Mitzrayim every day throughout the year, however, does not require an action and thus is not found on the Rambam's list.
There are other commentaries who point out that there is in fact no separate Mitzvah (besides on the night of Pesach) to remember Yetzias Mitzrayim. Rather, remembering how Hashem saved us from Egypt falls under the general category of believing in השגחת פרﾁaÀ Yﾁaﾈﾕ, though, derives the Mitzvah from a different Posuk which says, "זכור את היום הזה אשר יצאתם ממצרים," "remember this day on which you departed from Mitzrayim" (שם פסוק ג'). The Rambam (שם) then expounds upon this by drawing a connection to the observance of Shabbos, where the word "זכור," "remember" is also used (שם כ':ח'). HaRav Soloveitchik explained that this word זכור"" requires "זכירת תמיד," that one must "always remember." Just like one remembers Shabbos all week, by saying, for example, the daily Shir Shel Yom which always mentions Shabbos (such as היום יום ראשון בשבת...""), and one then amplifies this remembrance once a week by saying Kiddush on Shabbos, so too regarding Pesach, part of the Mitzvah of remembering Yetzias Mitzrayim is by definition fulfilled by remembering it every single day, and then once a year, it is amplified and elaborated upon. Therefore, the Rambam did not document remembering Yetzias Mitzrayim daily as a separate Mitzvah - because it isn't. It is clear from what the Rambam writes in Hilchos Kerias Shema (שם הלכה ג') that he considers it a Mitzvah to mention Yetzias Mitzrayim every day and night; he simply does not hold that it qualifies as a separate Mitzvah on the list of the Taryag Mitzvos for the above reasons.