At which events discounts are occuring?

Community-Created Courses Community-Created Courses Hub
1

Possibly a duplicate.
When do memrise discounts occurring? At which points?
And how much do they offer?
If I remember correctly there are a 50% discount at 10 day streak.

2

I saw a discount at reaching level 14.

3

2 days - 10%
5 days - 20%
10 days - 50%
But the last one I already can’t confirm because bought lifetime premium.