Ashwagandha

Was thinking about trying it. A friend recommended it to me on skype, but wanted to get other peoples thoughts on it. I just had a few questions on it.

1.Can I take it for a month and stop?
2.Will it reserve the dmg propecipa has done to me?(I only took one pill)
3.Are their any side effects I should be concerned about?
4. Can someone link me to the right Ashwaganha product on Ebay? (So I don’t order the wrong one there are tons of them)