Hello @Noa,

Thanks for your post! Happy to help.

If you are tracking a 'Sign up' event you could leverage a Funnel chart to create a cohort of users who perform a particular event within 'X' days of performing 'Sign up'. Here is an example from the Amplitude Demo,

Chart: https://analytics.amplitude.com/demo/chart/new/tc4nfta

Cohort: https://analytics.amplitude.com/demo/cohort/pp3vn0g 

*Please note, you are not able to view the population over time in the Cohorts tab for this type of cohort at the moment. As an alternative you could add the cohort to a uniques chart queried on 'Any event': https://analytics.amplitude.com/demo/chart/new/i5t6dd6 

To query on users who performed 'Sign up' more than 'X' days ago you could create a user segment filtered on the 'Sign up' event, then use the offset feature to manually specify that users performed 'Sign up' in an earlier date range. If you want to also add a filter to the segment so that the users also have to have performed 'Login' >= 1 in each month you can add a second filter on the user segment to specify the users have also performed 'Login' >= 1 once in each month when you are querying on a monthly interval. Here is an example user segment that is queried on users who performed 'Sign up' sometime in January 2022, but not in the last 30 days, and who also have performed 'Login' in each month: https://analytics.amplitude.com/demo/chart/new/af6qcto 

In this case, you will need to manually determine the offset window based on how many days ago you would like users to have performed the 'Sign up' event.

I hope this information is helpful! Let us know if you have any more questions.

- Jacenda