u/MysteriousMushroom70

I'm planning on visiting friends for the first time in germany, They told me about the deutschland ticket for an easy way of moving around the country while there, But there's limited information on it, It says it is a monthly subscription, but if I buy it lets say on the 20th of september, will it be vaild through the 20th of october? or do I have to pay for a second month as soon as October hits? Also i've read that buying it from Mopla is the best, is that true?