You can achieve this by using a list.

First define the list as a global and initialize it:

globals [ x_log ]

set x_log [ ]

with each step (tick) you can extend your list by

set x_log fput attribute x_log

this list now saves all of your attributes.

To perform operations on the list you have a variety of options:

https://ccl.northwestern.edu/netlogo/docs/dictionary.html#listsgroup

If you only need the latest n values of a list you can create a sublist:

if length x_log > n [

set x_log_sub sublist x_log 0 n ]

Use monitors to observe the lists while coding so you won't get any unwanted results.

In my example, the turtle randomly walks over a surface, saves the patches' color in the list x_log.

The sublist x_log_sub only remembers the last 5 items. The third monitor then calculates the mean of the last 5 entries.

Very useful your note Andreas, thank you!.

This may be overkill for what you're trying to do but ... the 'Time' extension in NetLogo provides some easy-to-use and flexible utilities for storing, and retrieving time series (see 'time:ts-create'); including saving/storing them and various functions for manipulating them.

Thank you dear Steven i will check this idea too.