If you don't want snails in your aquarium I would suggest that you wash the plant off before putting it in the aquarium. This may or may not work for you. It will however lessen the chance that you will get snails in your aquarium. You may also want to check with the store where you buy your fish and see if they have any fish that are preditors to snails and will control the population.
The other alternative is to buy aquarium plants as bulbs. You can probably get bulbs at your local fish store and that will probably zero out the chance that you will get snails in your aquarium from that plant. The bulbs will be dry when you buy them and the package will have instructions on how to start the bulb and maintain it.