Every pair on Strade has its trading times. A new pair opens at a set time; a pair that is delisted stops trading at a set time. Both are shown on the site in advance.

A new pair: Soon

Before the opening the pair is marked Soon in the market lists (on the Markets page, on the home page and in the pair selector on the trade page).
Its trade page shows Trading on BTC/USDT starts in 1d 02:13:45 (with the name of the pair), counting down every second, and the opening date and time in your time zone (set in Preferences).
No orders are accepted before the opening, also no orders placed in advance: the buy and sell buttons and the swap on this pair are inactive with Trading on this market starts on and the date. If you try anyway, you see Trading on this market has not started yet. Please wait for the opening time.
At the opening time the buttons become active by themselves, you do not need to reload the page. The order book and the chart stay empty until the first orders and trades. Market orders work after the first trade: Why was my market order rejected or not fully filled?

A pair being delisted: Delisting

A delisting is announced in advance in the news and in a notice on the site. Until the end time the pair is marked Delisting, and its trade page says Trading on BTC/USDT ends on the date and time, Open orders will be cancelled.
Until then you trade and cancel orders as usual.
At the end time trading on the pair stops for good: new orders are not accepted and nothing is filled any more, also stop-limit orders do not trigger.
Shortly after the end time all your open orders on the pair (limit, stop-limit and market orders) are cancelled. The reserved funds return to your available balance, and you get the usual "order cancelled" notification. You do not need to do anything.

After the end: Delisted

The pair is marked Delisted on the Markets page and in the pair selector, and it is no longer shown on the home page.
Its trade page says Trading on BTC/USDT ended on the date. Your order history and trades on the pair stay visible.
If you try to place an order, you see Trading on this market has ended. The pair has been delisted.
Deposits and withdrawals of the coin follow the announcement: deposits may stop before the end of trading, and withdrawals stay open until the date given in the announcement. Withdraw your coins before that date: How do I withdraw crypto?

A pause is something else: it is temporary, and trading continues after it. See Trading is temporarily halted.

Stay safe: Strade support never asks for your password, 2FA codes or seed phrase. Be careful with messages offering to "save" your coins from a delisting or to move your funds: they are scams.

When does a new pair open, and what happens when a pair is delisted?