so this is how it all started, i bought a humble bundle that included a dopus 12 light key, i then installed dopus and i think i might have started the 30 day pro free trial without putting my key in, then when the trial ended in the license manager it had the option to switch to light mode and it would restart dopus but it didn't restart and it just left me on the same page, i even tried installing a new certificate but it sais program certificate is not valid.
If you're using the key from the Humble Bundle, make sure you use the Register Product Token option in the Licence Manager, not the Install New Certificate option (unless you've already converted the Humble key into a certificate file).
Full instructions for redeeming the Humble keys are here: Humble Lifehacker Bundle - Directory Opus 12 Light Key Redemption Instructions
If that doesn't solve it, please email our Sales@ address with details of the key you are trying to install, and they can help from there. (Please do not post key details to the forum, as everyone can read it.)