Here are the reasons why an account would be closed/deleted:

1. You asked for it.
2. You did not use it for over a year (signed in at least once). Account that are not used are deleted after one year of inactivity.
3. The email address in your account is not valid anymore. This includes disposable/tmp/spam email addresses.
4. You used some kind of program/script/tool/bot/crawler to connect to the member area. There are no exception for any tool.
5. Creating multiple accounts to circumvent limits will lead to the closure of all of your accounts.
6. Any kind of data mining in the member area will lead to account closure.

Use the contact form, if you think closing your account was a mistake.

There is no API, so no you can't.

The alexa.com website was shut down May 1, 2022. The alexa top websites research list is based on the last updated csv file from Feb 1, 2023. The domains on the list plus the corresponding alexa rank will obviously not change anymore, however the other domain infos will still be updated.

It depends on the domain list. You can find the usual update time for every list here. (You need to login)

All times are UTC.

Current Time		UTC +/-	Timezone	Example
03:55 AM	03:55	-08:00	US Pacific Time	Los Angeles, Vancouver
04:55 AM	04:55	-07:00	US Mountain Time	Denver
05:55 AM	05:55	-06:00	US Central Time	Chicago
06:55 AM	06:55	-05:00	US Eastern Time	New York, Toronto
11:55 AM	11:55	+00:00	UTC	UTC
11:55 AM	11:55	+00:00	GMT / BST	London, Dublin
12:55 PM	12:55	+01:00	Central Europa Time	Berlin, Paris
07:55 PM	19:55	+08:00	China Standard Time	Shanghai, Beijing, Hong Kong
08:55 PM	20:55	+09:00	Japan Standard Time	Tokyo, Seoul

If you want to know what time this is in your Timezone, you can use the World Clock Meeting Planner or time.is.

It is unfortunately not possible to add the end date to the watchlist. The watchlist combines domains from different domain lists with different end dates. Also a domain can be in multiple domain lists at the same time with list specific end dates.
You can however use the "only Watchlist" filter on the specific list you want the end date from.

Deleted Domains do not have a Whois Record anymore. They are just like every "available-never-registered-domain" in that regard. If you register a Deleted Domain, it receives a brand new Whois Record and a new Creation Date. The same applies for Expired Domains that reach Pending Delete State. The domain will be deleted and the Whois Record resets.

If you want to keep the Whois Creation Date, you have to buy the domain before it drops (before it reaches pending delete state). That is possible for Godaddy Expired Domains and GoDaddy Closeout Domains for example. These domains are auctioned before they reach pending delete. It is not possible to keep the Whois Creation Date (Birth Year) for Pending Delete Domains and Deleted Domains. When you register one of those, you will automatically create a new Whois Record with a new Creation Date.

To make filtering and sorting possible, the data has to be gathered and saved localy. Requesting data on the fly is to slow and most resources are limited on how many requests you can do per minute/hour/day. That is why gathering the information beforehand is important. Periodically the domain data will be refreshed, but it is impossible to refresh it every day. So there is a chance that the values you see have changed. Some values can change rapidly. It is encourage to check the information yourself before making a buying decision! You can click on most values to verify them on the resource website.

It is not possible to keep the availability status up to date for all deleted domains. There are over 400 million deleted domains in the database and the availability has to be checked one by one. So yes, it can happen that the website is showing domains as available that were already registered again. It is annoying, but there is no technical solution for this issue.

You can't find Internationalized Domain Names, because IDNs are currently not supported.