Quote Originally Posted by Valda View Post
Спасибо, я запомню о этом.
Firstly, we use об in front of words starting with a 'true' vowel such as: а, о, э, у. Ы is a true vowel too but I don't think there's a word starting with Ы in Russian.
Secondly, запомнить is a transitive verb, unlike помнить, which can be both transitive and intransitive. So, given that you should have said:

Я запомню это
or
Я буду помнить об этом
or
Я буду помнить это

The first two examples (count from the top to bottom) have subtle differences in meaning though, but it depends on verb aspects, which you already know and are aware of I trust.
The third example means pretty much the same as the second one.

All of them are fine in your case, but I would prefer the first one over the others.