This is a really good question to consider when buying. :)
In the Magoosh product, there are about 25 hours of GRE lesson videos and 43 hours of explanation videos (explaining the solutions to each of our 1100+ practice questions). While you could get through everything in about a month if you are dedicating several hours of time daily to your studies, we usually recommend that students study for closer to 2-3 months. This is pedagogically better to prepare for the exam itself, but it is also important if you want to complete the material to be eligible for our score guarantee.
It might help to get a feel for pacing by looking at our study plans. Our 1 Month Study Schedule (Daily) will give you a good indication of the amount of work needed on a daily basis to prepare adequately and get through Magoosh materials. The number of hours required per days ultimately depends on your starting abilities and how many questions you answer incorrectly during studies. Hopefully that gives you a good starting idea! :)