It is probably not necessary to seal it, but it cannot hurt. Sealing it will help keep much water from getting down under the foundation. Use a polyurethane sealant made for concrete, they are available in the section with the bagged cement and morter mixes at the big boxes.
Polyurethane is best bet. I used PL concrete & masonry sealant. Worked great consider the following buy a qt. of mineral spirits for clean up, you can buy as self leveling or not (flat or sloped) this stuff takes a while to cure (above 40 degress) so no traffic over it