Some features require extra resources, for example sending emails (Google blocks port 25 outbound so sending emails needs to rely on external services. I am using mailgun and currently using about 4800 of the 10000 free emails), storing fuel data in SQL, storing media, etc. those features will eventually become paid and the engine block will change - cast iron is pretty much the free level that allows everything except emails, fuel streams, media storage, and visors. There will also be alluminum alloy and magnesium alloy - not sure what level of service will be there for each. But the iron cast will continue to exist as a free tier giving access to all features except those that require resources outside of the ST cloud. Some free features that do not follow that model exist, like browser registration, and account login (in the works). These will be free regardless.