I reply to my own post in case somebody can use it:
<%set paidstart=0%>
<%set paidend=0%>
<%loop link_results_loop~%>
<%if isPaidLink%>
<%if paidstart==0%>PAID START<%set paidstart=1%><%endif%>
<%else%>
<%if paidstart==1 and paidend==0%>PAID END<%set paidend=1%><%endif%>
<%endif%>
<%include link.html%>
<%~endloop%>
Code:
<%set paidstart=0%>
<%set paidend=0%>
<%loop link_results_loop~%>
<%if isPaidLink%>
<%if paidstart==0%>PAID START<%set paidstart=1%><%endif%>
<%else%>
<%if paidstart==1 and paidend==0%>PAID END<%set paidend=1%><%endif%>
<%endif%>
<%include link.html%>
<%~endloop%>