use the "frozen" value of a cell in calc

I’d want to reference a named cell in a formula, and use its immediate value, that is, the value it stores at the moment where the sheet is saved. The way to achieve that would be to add a “frozen” attribute to the cell, which modifies its behavior: the value it holds is “frozen” into the formula when the document is saved, and later the user must explicitly ask to update the formulas which reference this cell. Another way would be to create a new type of reference.
I need that to create a model with one sheet per month, which uses bus or train prices, mileage allowance, etc. stored in named cells, but keeps the correct values for past months whenever the rates change.

Does this feature exist, or is it possible to develop it?

“Does this feature exist …?” No, as far as I know.

“… or is it possible to develop it?” Programming Subs and assigning them to events: nearly everything possible in principle. I would not recommend this for many reasons.

“… create a model with one sheet per month …” As I deduce from own old experiences and from many questions (cries for help) in this forum and in others: Keeping data of same structure in more than one sheets is a source of problems arising on and on.

I am wondering what @JohnSUN would answer and hope he gets triggered by this comment.

Lupp rightly said “I would not recommend this for many reasons”. “stored … but keeps the correct values ​​for past months whenever the rates change”- This is not a task for the calculator (Calc), but for the database (Base)

@JohnSUN & @Lupp - Thanks for your comments!