I think you mean, "Can I keep an anemone with an marine betta I have a carpet anemone and wanted to know before I buy a marine betta"
This is what i found on the Marine Betta....
The Marine Betta, sometimes referred to as the Comet, is found in rocky crevasses, at depths up to 45 meters. It is a hardy and disease-resistant fish. A predator by nature, it assumes a "head down" position, with its false "eye spot" near the tail resembling the head of a moray eel.
The Marine Betta is not commonly kept in a reef-style aquarium, but it is reported to be safe with corals and anemones, however, it will eat all small fish and shrimp. It is nocturnal and requires hiding places to provide it shelter from bright lighting, being more active at dusk.