Where can I find SC2 trial keys with my purchased SC2 (digitally)?

[Handfoot]

I heard you get 2 trial keys per purchase of SC2. Where can you find them, because I purchased the game digitally so it didn't come with a box with trial cards and whatnot.

[Lefuu]

I purchased the game digitally

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[Handfoot]

Not fair.
Does anyone happen to have a trial key?