How to make the result of a function permanent

I would like to know if exists a formula that, if a condition is satisfied, return me the value stored in a cell. I know that I can use the feature "To Actual" or copy the cell and pasting it as value. I would like to automatize the formula itself, so that I don´t need to do it manually.

Example:

=IF(A1<A2=""; IF(A1=A2; A3; IF(A1>A2; A1))).

This works but the cell A1 is still the result of a formula; I would like that if A1>A2, A1 would be stored as his value, so that will never change anymore. Hope I could explain myself :)

Thanks for the help.