You can keep your trade open for as long or as short a period as you like. However please be aware that if you are using a multiplier with your trade, you will be charged a nightly financing fee.
It must also be noted that we will close your position the moment you have lost 100% of your invested amount. This is what we refer to as a "guaranteed stop-loss".
We published a funny article related to this on our blog, Fundamental Analysis: How To Pick Stocks For The Long Term
If you have any further questions in regards to this, please feel free to contact us via email at BUX Support.