In your Store Config there is a section called Google Analytics. Change "Use custom Javascript code" to Yes then in the box paste the following:

<-script>
(function (i, s, o, g, r, a, m) {
i['GoogleAnalyticsObject'] = r; i[r] = i[r] || function () {
(i[r].q = i[r].q || []).push(arguments)
}, i[r].l = 1 * new Date(); a = s.createElement(o),
m = s.getElementsByTagName(o)[0]; a.async = 1; a.src = g; m.parentNode.insertBefore(a, m)
})(window, document, 'script', '//www.google-analytics.com/analytics.js', 'ga');


ga('create', '***Enter Analytics code here***', 'auto', { 'allowLinker': true }); //<-- Enter your analytics code in here
ga('send', 'pageview');



// If your VevoPay is set up as a sub-domain like VevoPay.domain.com also use the following else delete it
ga(function (tracker) {
var linkerParam = tracker.get('linkerParam');
var c = jQuery('.PaymentFrame[src*="VevoPay.domain.com"]').attr('src'); //<-- Change domain to your domain name
jQuery('.PaymentFrame[src*="VevoPay.domain.com"]').attr('src', c + "&" + linkerParam); //<-- Change domain to your domain name
});
<-/script>


If you are using VevoPay as Sub-Domain then add the following to the head area of CreditCardInfo.aspx in VevoPay

<-script type="text/javascript">
(function (i, s, o, g, r, a, m) {
i['GoogleAnalyticsObject'] = r; i[r] = i[r] || function () {
(i[r].q = i[r].q || []).push(arguments)
}, i[r].l = 1 * new Date(); a = s.createElement(o),
m = s.getElementsByTagName(o)[0]; a.async = 1; a.src = g; m.parentNode.insertBefore(a, m)
})(window, document, 'script', '//www.google-analytics.com/analytics.js', 'ga');


ga('create', '***Enter Analytics code here***', 'auto'); //<-- Eneter the analytics code for the domain that the sub-domain belongs to
ga('require', 'linker');
ga('linker:autoLink', ['domain1.com', 'domain2.com', 'domain3.com']); //<-- Eneter all teh domains that your VevoPay processes for in this section
ga('send', 'pageview');
<-/script>


***Note: remove the - in each one of the <-script> and <-/script> tags after pasting.