The Spore ModAPI Launcher Kit has, on numerous occasions, proven extremely unreliable with the Steam version of Spore. As such, if you're thinking of buying Spore, it is strongly recommended to buy it either from Origin, GOG instead of Steam. Even the retail version is preferable if you don't mind being locked out of online features. If you already own the game on Steam, it is recommended to transfer your Steam Spore keys to Origin (which is free), then backup your creations and save data, uninstall the Steam version of Spore, and then install the Origin version in its place.
Investigation into a proper fix is ongoing, though remains fruitless thus far.