Is it obligatory to fast only three days, or three days for each day of non-compliance, for someone who swore by Allah, to himself, that he would commit to Surat Al-Baqarah and Ruqyah daily, but then was unable to commit?

It appears that you are required to offer expiation (kaffarah) only once, unless you intended to repeat the oath by repeating the breaking of it.

However, if you did not utter an oath, then there is nothing upon you, for the Prophet, peace and blessings be upon him, said: "Indeed, Allah has forgiven my nation for what they merely think to themselves, as long as they do not act upon it or speak of it."

The expiation for an oath is in the order mentioned in the verse: "Its expiation is the feeding of ten poor people from the average of what you feed your own families, or clothing them, or freeing a slave. But whoever cannot find [each of these] – then a fast of three days."

It is not permissible to resort to fasting unless one is unable to feed, clothe, or free a slave. The amount for the feeding expiation is one and a half kilograms of the staple food of the country.

If one cannot find poor people in their country, they should send the expiation to the nearest country where there are poor people. It is also permissible to give the expiation to a trustworthy charitable organization.