Check for valid key

Also any option to see license activations in admin dashboard

Using the www.remarpro.com version no. But with our paid extension yes (here), it comes with manage pages to view and edit customer license keys from the admin dashboard.

is there a way to check license key if it’s valid or not? I mean the key which is not activated yet, just to see if the entered value is a valid key or not.

With the api no, since the activation endpoint already does the process and there is not need to do a previous request just to validate.

But if you wish to do this, you can accomplish this by using the LicenseKey model class:

<?php
use LicenseKeys\Models\LicenseKey;

if ( LicenseKey::find( '[a-customer-license-key]' ) ) {
    // FOUND
} else {
    // NOT FOUND
}

a query to db for retrieving that information with a custom plugin?

You can always use the model explained above to query the db, the model uses the FindTrait.php, which you can review, to provided proven query functionlity.

An example:

<?php
use LicenseKeys\Models\LicenseKey;

$license_keys = LicenseKey::fromOrder( $order_id );

If you wish to extend the query functionality to add custom queries you can do this bu creating you own model that extends from the existing one:

<?php
use WPMVC\MVC\Collection;
use LicenseKeys\Models\LicenseKey as Model;

class MyLicenseKey extends Model
{
    public static function all()
    {
        $license_keys = new Collection;
        // TODO QUERY CODE
        return $license_keys;
    }
}