You alone probably cannot offer support. It usually means enterprise support, search for MariaDB or MongoDB services and see what they are doing.
The bottom line is that, in order for the big companies to use your product, you have to offer support to it, in any environment/timezone, and to all your product dependencies (example if it uses a database you have to to that as well, or have a collaboration with another company).
I say "big", because if someone is "small" probably will not have the money to pay for a support.
You can find many resources on this field, this is one of them I actually attended Open source slush by one of the MySQL and MariaDB founders.
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