Forty-nine is seven squared, and every significant use of it is a seven of sevens rather than a use of forty-nine as such.
Leviticus 23:15-16 commands that from the day the sheaf of the first barley is brought, seven complete weeks be counted, forty-nine days, and that the festival be held on the fiftieth. This is the Counting of the Omer, still observed nightly in Judaism between Passover and Shavuot, each evening announced with its number in weeks and days. The count is spoken aloud, which makes it one of the few commandments performed purely by enumeration, and it turns the interval between the exodus and the giving of the Torah into a structure rather than a gap.
Leviticus 25 applies the same arithmetic on a larger scale. Seven sabbaths of years, seven times seven, forty-nine years, are counted, and the fiftieth is the Jubilee, in which land returns to its original holders and debt slaves go free. Whether the Jubilee was ever practised as legislated is doubted by historians, and there is no clear record of a Jubilee year being observed, but the scheme is one of the most striking pieces of economic thought in the Hebrew Bible: it makes land inalienable and treats every sale as a lease.
Later Kabbalistic practice attaches a further structure to the Omer, pairing each of the forty-nine days with a combination of seven lower sefirot taken two at a time, seven weeks of seven qualities. That system is medieval and Lurianic, developed at Safed in the sixteenth century and after, and it should not be projected back onto Leviticus.