About 'Forget'
Someone told me that we don't normally use gerund after 'Forget' in the Negative sentences or Questions. So we can't use 'Infinitive' in that situation. Is it really true? If so, how can we say when we need to talk about a decision that we are not going to do? 1. I will never forget meeting him. 2. I will never forget to meet him. (According the person who told me like above, 2 sentence is incorrect.)I already knew the difference when it comes to combing Forgot with Gerund or Infinitive.
I just want to know if 'I'll never forget to meet you' is grammatically correct or not. According to Mr. Kesocascay, I need to make a new sentence with 'remember' instead of using 'never forget to meet'. I understand his explanation. But I am still wondering if that sentence is grammatically wrong.

Question

About 'Forget' 
Someone told me that we don't normally use gerund after 'Forget' in the Negative sentences or Questions. So we can't use 'Infinitive' in that situation. Is it really true? If so, how can we say when we need to talk about a decision that we are not going to do? 1. I will never forget meeting him. 2. I will never forget to meet him.  (According the person who told me like above, 2 sentence is incorrect.)I already knew the difference when it comes to combing Forgot with Gerund or Infinitive.
I just want to know if 'I'll never forget to meet you' is grammatically correct or not. According to Mr. Kesocascay, I need to make a new sentence with 'remember' instead of using 'never forget to meet'. I understand his explanation. But I am still wondering if that sentence is grammatically wrong.

Answer

"Forget" is actually a irregular verb and quite a weird one at that. 
In past form, it is "Forgotten/forgot" versus what it should be; "forgeted". In case of this usage, "forget", when in negative form, changes to one of its antonyms;
"I will never forget meeting him" could be used if few cases, but "forget" is in negative and will commonly be replaced with "remember" or be rewritten entirely.
1: "I will always remember meeting him/I will remember our meeting"
2: "I won't forget the day we met."
When it comes to a -to verb, then "not/won't" is used.
1: "I won't forget to meet him." ("not" is not used with "forget", if so, it turns into "will not/won't")

Answer

The verb "forget" is a special case. The verb takes either a gerund or an infinitive as an object, but the meaning changes with each. Two other verbs with this characteristic are "remember" and "stop". Your friend is mistaken.

Answer

In America, we would normally say "I will never forget you." or "I will always remeber you."
The sentance you wrote emplyies that you will not forget to meet that person. That would be ok if you were talking about literally meeting that person in a specific place. But if your talking about an introduction type meeting, then one of the two sentanced I wrote is what would be used.

Answer

To make it short,It is not grammaticlly wrong but its preferably better if you use a positive statement on the sentence which is "I will always remember meeting him/ I will always remember to meet him"

Answer

I'll never forget to meet you is grammatically all right.