You can ofcource help us by signing up for the premium version. But MixForms is currently in the startup phase. This is great news for you because you will get the premium plan for free until we decide that the startup phase is over, and at least until august 2017!
If you want to help us already, you can give us a donation as well. Because it is hard to continue development and support for this free plugin without contributions from users like you. If you enjoy using MixForms and find it useful, please consider to upgrade your plan to Premium (and takes lot of extra functionality) or donate. Your donation will help encourage and support the plugin's continued development and better user support.