From the day, you create a demo account on MT4 of VT Markets. You have 90 days of valid period.

On the other hand, MT5 have 30 days of valid period, since the last day you login your demo account. In other words, if you continually login the MT5 demo account for each 30 days, your account will not be expired.

If your demo account is expired, you can login your Client Portal to create a new demo account by clicking "Account" > "Demo accounts" and re-apply your application.